Examples of prefixes in English. Prefixes in English rules

The formation of words can occur with the help of prefixes, which, although they change the meaning of words, do not change its belonging to one or another part of speech. Many prefixes have their own meaning and, as a result, are stressed. There are no prefixes characteristic only for any part of speech in the English language.

The prefix anti- corresponds in Russian to the prefixes “anti-”, “anti-”:

anti-fascist – anti-fascist
anti-aircraft – anti-aircraft

The prefix counter- corresponds to the Russian prefix “konr-“, “anti-“:

to counter act – to counteract

The prefix dis- will give a negative meaning; often translated into Russian with the prefixes ne-, dez-, bes-, bez-:

dis obedient - naughty
dis order - disorder
dis honest – dishonest
dis appear - disappear

The prefix ex- means “ex”:

ex-champion - ex-champion

The prefix en- often means “to do” and forms a verb from adjectives and nouns:

to en large – increase, make large
to en circle – surround, make a circle

The prefix fore- means “before”:

fore head - forehead

The prefix inter- has the meaning “between”, “among”, “mutually”:

inter national - international

The prefix il- means negation. Used if the word begins with the consonant l:

il legal - illegal
il literate - illiterate

The prefix im- means negation. Used if the word begins with the consonants b, m, p.

im mortal - immortal
im balance - instability
im parity - inequality

The prefix in- gives the opposite meaning. Words with the prefix in- need to be remembered:

in consistent - incompatible
in definite – uncertain; unclear; indifferent
in dependence - independence

The prefix ir- means negation. Used if the word begins with the consonant r.

ir responsible - irresponsible
ir relevant – inappropriate; irrelevant
ir regular – incorrect; irregular

The prefix mis- means “incorrect, incorrect”:

to mis understand - misunderstand

The prefix non- means negation or absence:

non-alcoholic – non-alcoholic
non-essential - insignificant

The prefix over- is often translated into Russian by the prefixes over-, pere-, super- or excessively.

to over pay – overpay
over-active – overactive
to over-estimate – to overestimate

The prefix post- is used with the meaning “after”:

post-war - post-war

The prefix pre- is used with the meaning “before”, “earlier”:

pre historic - prehistoric

The prefix sub- corresponds to the Russian prefix “under”:

sub-tropical – subtropical
sub marine – underwater
sub way – subway, metro

The prefix super- means “over”:

super natural – supernatural
to super charge - overload

The prefix trans- corresponds to the meaning “through”, “between”:

trans atlantic - transatlantic
trans national - international

The prefix re- is used with the meaning “again”, “again” (often corresponds to the Russian prefix “re”):

to re write - rewrite
to re do - redo

The prefix un- gives the opposite meaning:

to un do – undo what has been done; destroy
un able - unable uncomfortable - inconvenient

The prefix ultra- is used with the meaning “ultra”, “over”:

ultra-modern – ultra-modern
ultra violet - ultraviolet

The prefix under- means negation and is often translated into Russian by the prefixes “under-” or has the meaning “under something”:

to under estimate - to underestimate
under ground - undergroundviolet - ultraviolet

Negative prefixes of English verbs.

Un-

Very rarely used with verbs. Matters "delete"

Unscheduled – remove from schedule

Unfriend – remove from friends

De-

Negative prefix, which often remains in Russian (de-) or translated as "once-".

Deactivate - deactivate,

Decode - decode,

Decommission - to write off,

Decompose- disassemble,

Deconstruct- disassemble,

Decontaminate- disinfect,

Decrease - reduce

Dis-

Negative prefix, often translated as "Not" or “des.”

Disagree - disagree

Disfigure - to disfigure,

Disinfect - to disinfect,

Disinherit - to disinherit,

Disintegrate - to disintegrate,

displease - not to like,

distrust - not to trust.

Mis-

Matters "wrong".

Misdiagnose - make an incorrect diagnosis,

Misinform - incorrectly inform,

Misinterpret - to misinterpret,

Mislead - to mislead

Misplace - put in the wrong place

Misspell - make spelling mistakes,

Mistake - to make a mistake

Under-

Matters "under".

Underground- subway

Underwear- underwear

RE-

Matters “do it again, redo it.”

Rewrite- rewrite

Replay- replay

Refill– refill

Over -

Points to an excessive degree of something.

Overcook- digest

Overcrowd- overfill

Oversleep- oversleep

Un- / im- / ir- / il- / dis- / in-

Negative prefixes.

Illegal- illegal

Dislike- not to love

Unusual- unusual

Irregular- incorrect

Impossible- impossible

Since the use of prefixes in English is difficult to interpret by rules, I advise you to learn the basic words by heart. And to test yourself, perform a few exercises below. Good luck!

Exercise 1. Form new words using prefixes and translate into Russian.

Prefix in-: complete -, edible -, correct -, capable -, accurate -, visible -, flexible -.

Prefix im-: possible -, perfect -, probable -, pure -, precise -, practical -, mobile –.

Prefix ir-: relevant -, regular -, respective -, responsible -.

Prefix il-: legal -, liberal -, literate -.

Prefix un-: stable -, fair -, familiar -, to freeze -, to fix -, fit –, foreseen -, to hang -, heard

Exercise 2. Form negative nouns using the prefixes un-, in-, dis-, mis-, de-

Honesty-

Certainty-

Security -

Dependence-

Importance-

Employment -

Connection-

Activation -

Belief-

Ability

Exercise 3. Complete the negative prefixes with the following adjective.

an __friendly look

an __interesting book

an __natural color

an __important task

an __possible answer

an __personal letter

an __definite article

an __correct answer

Direct speech

an __regular verb

an __responsible person

Exercise 4. Form negative adjectives using prefixes un - or in - :

Happy, lucky, attentive, capable, comfortable, known, dependent, clean, necessary, pleasant, expensive, human, popular, expressive, definite, real, countable, direct, convenient, accurate

Exercise 5 . Replace phrases one in a word

Example: not countable - uncountable

Not necessary –

Not safe -

Not tidy

Not breakable -

Not regular -

Not real -

Not expensive -

Not happy -

Not possible -

Not usual-

Not comfortable -

Not direct -

Not interesting -

Not patient -

Not convenient -

Not popular -

Exercise 6. Choose the correct prefix to make negative forms of the adjectives.

1) He was short and overweight and generally fairly __attractive.

2) He’s a good teacher, but tends to be a bit __patient with slow learners.

a) un-; b) in-; c) im-; d) dis- .

3) It is an __logical statement, because if one part is true, then the other must be false.

a) dis-; b) il-; c) in-; d) un- .

4) It is __ polite to point at people.

a) dis-; b) im-; c) in-; d) un- .

5) My friend is very __responsible, he never does anything in time.

6) He’s very __patient. He can’t work as a teacher.

a) dis-; b) im-; c) in-; d) un- .

7) He’s an __forgiving person. He never forgives people.

a) dis-; b) ir-; c) in-; d) un- .

Answers :

Exercise 2 .

Dishonesty, Uncertainty, Insecurity, Independence, Unimportance, UnemploymentDisconnection, Deactivatio,

Disbelief

Exercise 3.

an unfriendly look, an uninteresting book, an unnatural colour, an unimportant task, an impossible answer,

an impersonal letter, an indefinite article, an incorrect answer, indirect speech, an irregular verb, an irresponsible person

Exercise 4 .

UN + Happy, lucky, comfortable, known, clean, necessary, pleasant, popular, real, countable

IN + Attentive, capable, dependent, expensive, human, expressive, definite, direct, convenient, accurate

Exercise 5.

1 unnecessary, 2 unsafe, 3 untidy, 4 unbreakable, 5 irregular, 6 unreal, 7 inexpensive, 8 unhappy, 9 impossible, 10 unusual, 11 uncomfortable, 12 indirect, 13 uninteresting, 14 impatient, 15 inconvenient, 16 unpopular

Exercise 6.

1 d, 2 c, 3 b, 4 b, 5 b, 6 b, 7 d

Good luck in learning English!

Prefixes and suffixes in English are so-called affixes, that is, parts of a word (prefix, suffix or ending), which in linguistics are opposed to the root of the word and express a certain meaning. Affixes that are added before the root are called prefixes, and after the root are called suffixes. You will find the meaning of English prefixes and suffixes in the tables below, which will become your good helpers in determining the part of speech of a word, positive or negative meaning.

Knowing the meanings of prefixes and suffixes will help you express thoughts more freely in English when reading literature in English - guess the translation of words by root and quickly navigate when listening.

Today I have prepared a summary table of prefixes and suffixes in the English language, which, in my opinion, is quite clear and easy to use. I would like to add that if at one time I had such a summary of affixes, then English words would be remembered much faster. But first, refresh your memory by watching this video about prefixes and suffixes - although the animation is for children, the content is quite serious.

No.	Affix	Meaning	Example/Translation
Prefixes
1	anti-	against	anti-American (anti-American), anti-humane (anti-humane)
2	co-	with or together	co-worker (colleague) co-operate (to collaborate)
3	counter-	against or opposite	counterproductive (leading to counterproductive results) counteract (to hinder, oppose, resist)
4	ex-	former	ex-champion (former champion), ex-prisoner (former prisoner)
5	extra-	outside or beyond	extracurricular (extra-curricular; optional, optional), extracellular (extracellular)
6	inter-	between, among, mutual	interact (interact, influence each other), inter-branch (inter-industry)
7	mis-	wrongly	mislead (to mislead), misinform (incorrectly inform; mislead)
8	out-	do better than	outlive (to survive (someone/sth.)), outpace (to get ahead; go, run faster)
9	over-	too much	overcooked (overexposed, boiled), overflow (overflow, go beyond)
10	post-	after	post-war (post-war), post-tax (after taxes, post-tax)
11	pre-	before, earlier (Rus. do-)	pre-war (pre-war), pre-purchase pre-purchase, before purchase, before purchase (about events (actions, feelings, etc.) occurring before the purchase of a product (service))
12	re-	again or back	rebuild (rebuild, restore, reconstruct), rewrite (rewrite)
13	sub-	below, under	subconscious (subconscious), subdivision (division)
14	ultra-	extreme, extraordinary	ultra-compact (ultra-compact), ultrasonic (supersonic, ultrasonic)
15	under-	too little	underused, underweight

Suffixes of nouns
1	-ee	passive meaning	employee (employee; hired worker), interviewee (interviewee, giving an interview)
2	-er, -or	notes a job	a teacher (teacher), a director (director)
3	—ian	denotes nationality	Hungarian (Hungarian), Bulgarian (Bulgarian)
4	-ist	belonging to a political or scientific area	communist (communist), materialist (materialist)
Abstract nouns
5	-age	verb - noun	to marry - marriage (get married, get married - marriage)
6	-ance/-ence	adjective - noun	important - importance (important - importance)
7	-dom	adjective, noun - noun	wise - wisdom (wise - wisdom), king - kingdom (king - kingdom)
8	-hood	noun - noun	child - childhood (child - childhood)
9	-ion/-tion/-sion	verb - noun	to restrict - restriction
10	-ment	verb - noun	to develop - development (develop - development)
11	-ness	adjective - noun	weak - weakness (weak - weakness)
12	-ship	noun - noun	friend - friendship (friend - friendship)
13	-ure	verb - noun	to press - pressure
Suffixes of adjectives
14	-able, -ible	verb - adjective	to change - changeable (change - changeable)
15	-al	noun - adjective	culture - cultural (culture - cultural)
16	-ant, -ent	verb - adjective	to insist - insistent (insist - persistent)
17	-ful	noun - adjective	doubt - doubtful (doubt - doubtful)
18	-ish	1. nationality 2. rather or somewhat (partly)	1.Scott - Scottish (Scottish - Scottish) 2. child - childish (child - children's), red - reddish (red - reddish)
19	-ive	noun, verb - adjective	to talk - talkative
20	-less	lack of quality noun - adjective	home - homeless (home - homeless)
21	-ous	noun - adjective	glory - glorious (glory - glorious)
22	-proof	protected noun - adjective	waterproof (waterproof, fireproof (fireproof, fireproof)
23	-y	to be like or having the quality of noun - adjective	oil - oily (oil - oily), rubber - rubbery (rubber - rubber) e.g. oily hair e.g. Food such as meat that is rubbery is difficult to chew.
Suffixes of verbs
24	-en	make or become more	lengthen (lengthen; increase), strengthen (strengthen; strengthen)
25	-fy	adjective - verb	simple - simplify (simple - simplify)
26	-ize	noun - verb	sympathy - sympathize (sympathy - sympathize)

Now let's take a closer look at some prefixes and suffixes. So, if you know how to say these in English adjectives, How bright, dark, hard, loose, soft, then adding the suffix -en to their stem, you get verbs with the corresponding value:

Suffix -en
Adjective (what?) / adjective	Verb (what to do?)/ verb
bright	brighten	bright, shiny - add shine; brighten
dark	darken	dark - darken
hard	harden	solid - harden, harden
loose	loosen	free, spacious - loosen, untie
soft	soften	soft - soften
weak	weaken	weak - to weaken
broad	broaden	wide - expand
less	lessen	smaller - reduce
light	lighten	light - to brighten; become brighter, brighten
short	shorten	short - shorten; reduce
wide	widen	wide - expand
long	lengthen (mind the spelling)	long - lengthen; increase
strong	strengthen (mind the spelling)	strong - to strengthen; strengthen

Negative prefixes

Which negative prefix should I choose?
There is no clear rule, so you should be guided by the established usage of words in the language.

before the letter l the prefix in- turns into il- e.g. legal - illegal (legal - illegal)
before the letter r the prefix in- turns into ir- e.g. responsible - irresponsible (responsible - irresponsible)
before the letters m, p the prefix in- turns into im- e.g. mobile - immobile (mobile - stationary),
patient - impatient (patient - impatient)

Task 1: Match some affixes (prefixes and suffixes) with their meanings.

There are a number of negative prefixes in English - negative prefixes. Today we'll talk about them. After completing the theory on negative prefixes exercises in order to better understand the material.

The most common negative prefixes used in English are:

in- , un- , im- , il- , ir- , non- , de- , dis- , mis- , a- , anti-

The bad news is that the use of prefixes, like other aspects of word formation in the English language, is difficult to interpret by rules, and therefore you will mainly have to rely on your memory and perseverance. Still, there are some rules, replete with exceptions, regarding negative prefixes.

Let's get started and systematically study negative suffixes for different parts of speech.

Negative prefixes of English adjectives.

Prefix	Meaning and usage
	Negative prefix. With its help, the bulk of negative adjectives are formed.	unable - unable, unaware - ignorant, uncertain - uncertain, unclear - unclear, unfriendly - unfriendly, unhelpful - useless, uninformed - uninformed, unknown - unknown, unpleasant - unpleasant, unpredictable - unpredictable
	A prefix with a negative meaning, which is mainly used before ac/c	Inaccessible - unattainable, Inaccurate - inaccurate, Inadequate - inadequate, Incapable - incapable, Incomplete - unfinished, Incredible - incredible. Exceptions: indefinite, inevitable, infinite, inflexible, informal, insecure, insignificant, invalid, invariable, invisible, involuntary.
	Used only before l.	Illegal - illegal, Illegible - unclear, illegible, Illiterate - illiterate, Illogical - illogical Exception: disloyal
	Used only before r.	Irrational - irrational, Irregular - incorrect, Irrelevant - inappropriate, Irreparable - incorrigible, Irresistible - irresistible, Irresponsible - irresponsible, Irreversible - irreversible.
	Used before p, less often before m.	Immature - immature, Impatient - restless, Imperfect - imperfect, Impossible - impossible, Imprecise - inaccurate.
	Cases of using dis- must be remembered	Disagreeable - unpleasant, Dishonorable - shameful, Dishonest - dishonest, Disloyal - disloyal; Distasteful - disgusting, distrustful - distrustful.
	Cases of using non- must be remembered	Nonexistent - non-existent, Nonmetallic - non-metallic, Nonpartisan - non-partisan, Nonresident - not living here.

Pay attention to the spelling of words with the prefix non-. Most of them have two spellings (with and without a hyphen):

Non-existent or nonexistent.

However, some are written only without a hyphen - such as nonmetallic. This is why I still tend to write without a hyphen in all cases, to avoid unnecessary errors.

Negative prefixes of English verbs.

Prefix	Meaning and usage
	Very rarely used with verbs. Means “delete”	Unscheduled – remove from schedule Unfriend – remove from friends
	A negative prefix, which often remains in Russian (de-) or is translated as “raz-”.	Deactivate - deactivate, Decode - decode, Decommission - to write off, Decompose - to disassemble, Deconstruct - to disassemble, Decontaminate - to disinfect, Decrease - to reduce, Deform - to deform, Derail - go off the rails.
	A negative prefix, often translated as “not” or “dis”.	Disagree - disagree Disfigure - to disfigure, Disinfect - to disinfect, Disinherit - to disinherit, Disintegrate - to disintegrate, displease - not to like, distrust - not to trust.
	Means “wrong”.	Misdiagnose - make an incorrect diagnosis, Misinform - incorrectly inform, Misinterpret - to misinterpret, Mislead - to mislead Misplace - put in the wrong place Misspell - make spelling mistakes, Mistake - to make a mistake Misunderstand - misunderstand.

Negative prefixes of English nouns.

The negative prefix de is used by nouns formed from verbs with de-:

deflation, decomposition, deactivation, decontamination

The prefix dis is used by nouns formed from verbs or adjectives with the prefix dis.

Disability, disagreement, disbelief, disinfection, disintegration, disloyalty, displeasure, distaste, distrust

In- (il-, im-, ir-)

These prefixes have nouns formed from corresponding adjectives.

illiteracy, immaturity, imperfection, impossibility, inaccessibility, inaccuracy, inappropriateness, incapability, incompatibility, inconsistency, infinity, inflexibility, insecurity, insufficiency, invalidity, invisibility, irrationality, irregularity, irresponsibility.

The negative prefix mis is used by nouns formed from verbs with this prefix:

Misconduct, misdiagnosis, misinformation, misinterpretation, misspelling, mistake, mistrust, misunderstanding

The negative prefix non is typical for singular nouns:

nonconformist / nonconformity, nonexistence, nonintervention, nonsense

The negative prefix un is used by nouns formed from adjectives with the prefix un:

unawareness, uncertainty, unpleasantness, unpredictability

Negative prefixes are exercises.

Let's practice using negative prefixes a little.

Exercise 1. Form negative nouns using the prefixes un-, in-, dis-, mis-, de-

Honesty,
Certainty
Security
Dependence
Importance,
Employment
Connection
Activation
Belief,
Ability

Exercise 2. Complete the negative prefixes with the following adjective.

an __friendly look
an __interesting book
an __natural color
an __important task
an __possible answer
an __personal letter
an __definite article
an __correct answer
__direct speech
an __regular verb
an __responsible person

Exercise 3. Form negative adjectives using the prefixes un- or in-

Happy, lucky, attentive, capable, comfortable, known, dependent, clean, necessary, pleasant, expensive, human, popular, expressive, definite, real, countable, direct, convenient, accurate

Exercise 4. Replace phrases with one word

Example: not countable - uncountable

Not necessary –
Not safe -
Not tidy
Not breakable -
Not regular -
Not real -
Not expensive -
Not happy -
Not possible -
Not usual-
Not comfortable -
Not direct -
Not interesting -
Not patient -
Not convenient -
Not popular -

Exercise 5. Fill out the table according to the sample.

Adjectives: useful, doubtful, expensive, correct, clean, interesting, natural, healthy, important, polite.

artificial, rude, dirty, cheap, wrong, boring, sick, insignificant

Exercise 6.

Choose the correct prefix to make negative forms of the adjectives.

1) He was short and overweight and generally fairly __attractive.

2) He’s a good teacher, but tends to be a bit __patient with slow learners.

a) un-; b) in-; c) im-; d) dis- .

3) It is an __logical statement, because if one part is true, then the other must be false.

a) dis-; b) il-; c) in-; d) un- .

4) It is __ polite to point at people.

a) dis-; b) im-; c) in-; d) un- .

5) My friend is very __responsible, he never does anything in time.

6) He’s very __patient. He can’t work as a teacher.

a) dis-; b) im-; c) in-; d) un- .

7) He’s an __forgiving person. He never forgives people.

a) dis-; b) ir-; c) in-; d) un- .

Answers:

Dishonesty,
Uncertainty
Insecurity,
independence,
Unimportance,
Unemployment
Disconnection,
Deactivation
Disbelief

an unfriendly look
an uninteresting book
an unnatural color
an unimportant task
an impossible answer
an impersonal letter
an indefinite article
an incorrect answer
indirect speech
an irregular verb
an irresponsible person

UN + Happy, lucky, comfortable, known, clean, necessary, pleasant, popular, real, countable

IN + Attentive, capable, dependent, expensive, human, expressive, definite, direct, convenient, accurate

1 d, 2 c, 3 b, 4 b, 5 b, 6 b, 7 d

Hope, use of negative prefixes in English did not become a difficult topic for you.

Attached to the beginning of a word in order to change the meaning of the word. Knowing the meaning of the prefix and the meaning of the word itself, we can understand the meaning of the newly formed word. For example, the word comfortable (convenient), used with attachment un- , which gives the meaning of negation, changes its meaning to the exact opposite - uncomfortable (inconvenient).

Interesting fact: the word itself prefix (prefix) contains the prefix pre- , which means "before". And the root word fix means "to fasten" or "to fix". So the meaning of the word prefix - "place before".

Prefixation, or the process of adding a prefix to a word, is a common way of creating new words in the English language.

Prefixes in English with the meaning not

The most common prefixes in English are those that express negation. The meaning of the word is reversed.
a - immoral (immoral)
an - anaerobic (anaerobic - not requiring air)
ig - ignoble (mean, noble - noble)
il - illegal (illegal)
im - imbalance (imbalance)
in - inadequate (inadequate)
ir - irregular (irregular)
non-nonstop (non-stop)
un-unusual (unusual)

Prefixes in English with the meaning bad, wrong (bad, wrong)

dys-dysfunction (dysfunction),
mal - malocclusion (malocclusion),
mis - misspelling (wrong spelling)

Prefixes in English with the meaning against (against)

anti-anti-inflammatory (anti-inflammatory),
contra - contraindication (contraindication),
counter - countermeasure (countermeasure)

Prefixes meaning negation, removal

de - deactivate (deactivate),
dis - disappear (disappear)

Prefixes in English with the meaning before (before), already (already)

ante-antebellum (pre-war),
fore-foresight (foresight),
pre-preassembled (pre-assembled)

Prefixes that increase or decrease numerical values

Developing technologies especially often use prefixes for measured quantities. As our technological and computing devices become smaller and smaller, prefixes tend to get smaller too:
mili- number multiplied by 10 -3,
micro- number multiplied by 10 -6,
nano- number multiplied by 10 -9,
pico- number multiplied by 10 -12.

And these devices need more and more memory, so set-top boxes are also “growing”:
mega- a number multiplied by a million is 6 zeros,
giga- number multiplied by a billion - 9 zeros, gigabyte - billion or billion bytes
tera- a number multiplied by a trillion is 12 zeros, terabyte - trillion bytes
peta- a number multiplied by a quadrillion is 15 zeros.

It should be noted that these prefixes are used not only in English, but throughout the world, and their roots come from antiquity, from Greek and Latin.

Other common prefixes in English

Consoles	Meaning	Examples
auto-	auto	automobile(automobile)
bi-	double	bicentennial(bicentennial), binomial(binomial)
co-	joint	cooperation(cooperation)
di-	double	diatomic(diatomic), dipole (dipolar)
down-	down	downshift(downshift), downregulation
extra-	external	extracellular(extracellular)
hemi-	half	hemisphere(hemisphere)
hyper-	a lot, excess	hypercalcemia(hypercalcemia)
hypo-	little, not enough	hypothesis(hypothesis)
inter-	between	intermediate(intermediate)
intra-	inside, internal	intracellular(intracellular)
mid-	average, in the middle	mid-autumn festival(Mid-Autumn Festival)
mini-	mini,	miniature(miniature)
mono-	single, mono	monotonous(monotone)
multi-	many, more than one	multiplex(multiplex)
over-	excess, super-	overexpression(overexpression), overcoat(coat)
para-	besides, beyond	paranormal(paranormal), paramedic(paramedic)
per-	through	percutaneous(subcutaneous)
post-	after	postcolonial(postcolonial)
pro-	in favor	pro-science(pro-scientific)
re-	again, again	reestablish(restore)
self-	self-	self-cleaning(self-cleaning)
semi-	partially, half	semiarid(semi-arid)
sub-	below, below, under	subzero(below zero)
super-	higher, more than, super	supermarket(big store)
trans-	through, across	transatlantic(transatlantic)
under-	below is not enough	underexposure(insufficient exposure)
up-	up, increasing	upshift(overdrive), upregulation(increased activity)

Not all words begin with prefixes

There are many words in English that look like they start with a prefix, for example: ex- V exercise (exercise) And excommunicate (excommunicated), inter- in a word interesting (interesting), per- in words perhaps (possibly) and period (period). But these are not prefixes and you should not try to decipher the meaning of these words based on the meaning of the “prefix”.

When a hyphen is added with prefixes.

Hyphens are usually used in the following cases:

with attachments ex- And self- always use a hyphen: self-conscious (conscious), ex-student (former student);
if the main word is a proper noun - un-American (non-American);
if the main word begins with the same vowel as the prefix ends de-escalation (de-escalation), pre-eminently (to the highest degree) re-entry (entrance into the dense layers of the atmosphere). However, there are well known cases where the hyphen becomes optional, e.g. cooperate, coordinate .
Use a hyphen when a word might cause confusion or sound strange in a sentence: She told them to re-cover the will after they took water. (She told them to cover the well again after they had taken the water.)
A hyphen is needed here so as not to be confused with the word recover (restoration of health).

To summarize the above

In this article we looked at common cases of forming words using prefixes. But it should be noted that you need to be careful with prefixes: the same prefix can be written in several ways (for example: pre- And pro- ), some prefixes (for example, in ) have more than one meaning (“not” and “in”). However, being able to recognize prefixes can help us learn more new words.