English prefixes are of numerous types and make many extra words in the dictionary
DEFINITION & IMPORTANCE OF PREFIXES
A prefix is a kind of subdivision found in some words. It is likely to be:
(i) Placed before a possible English word, often with a hyphen.
(ii) Adding meaning to the partner word.
(iii) Able to occur in numerous other words.
(iv) Unable to be used alone as a word.
The last of these helps to separate prefixes from “roots” – meaningful word parts that are just as central as the word they are added to, such as house- in household. For more about roots within these pages, see 26. One Word or Two?, 106. Word-Like Suffixes and 172. Multi-Use Suffixes.
An example of a prefix is post- meaning “after” in words like post-natal, post-primary, postscript and postdate. It complies with (iv) despite the fact that there is also a separate word post, the reason of course being that the two meanings are entirely unrelated.
English prefixes are varied and widespread. Familiarity with them can help writers to be more concise and readers to more effectively guess the meanings of new words containing them (see 177. How to Guess Meanings in a Text). The aim here is not to give a full survey, of the kind that can easily be found elsewhere, but to give a flavour of the variety, in the hope of motivating further study.
THE PROBLEM OF PREFIX-LIKE SPELLINGS
Before prefixes are surveyed in detail, there is a need to appreciate that sometimes a spelling with the letters, meaning and position of a particular prefix is not a prefix as defined above. This is the case, for example, with post- in postpone and posthumous. Part of the reason is that it does not fulfil condition (i) above (-pone and -humous are not possible words).
An explanation of this alternative use of -post is that -post entered English in two different ways from the ancient language Latin (where it was a preposition – see 45. Latin Clues to English Spelling). The non-prefix use was adopted by English as part of a Latin word rather than as an addition to an existing English word, so that removing it is unlikely to leave a meaningful English word. The prefix use, on the other hand, was adopted later (my dictionary says it originated in Middle English, about 1000 years ago). It did not come linked to particular Latin words, but was available for addition to existing English ones, whether of Latin origin or not.
There is a similar situation with other prefixes derived from Latin prepositions:
Extra (“outside”) is not a prefix in extraneous or extrapolate, but it is in extraordinary, extramarital and extra-terrestrial.
Inter (“between”) is not a prefix in interest, interpret or intervene, but it is in international, interstate and intertwine.
Pre (“before”) is not a prefix in prefer, pretend or prevent, but it is in pre-existing, preheat, prehistoric and pre-natal.
Pro is not a prefix in produce, profile and protect, but it is in pronoun, proverb and pro-government.
Re (“again”) is not a prefix in receive, repeat or reveal, but it is in reclaim, re-evaluate, renew and resit.
Sub- is not a prefix in subsist, subvert or support, but it is in sub-division, submarine and sub-let (for synonyms of subdivision, see 162. The Language of Classification).
Super (“above”) is not a prefix in supersede or supervise, but it is in super-heated, superintendent, supernatural and supersonic.
Trans- (“across”) is not a prefix in transport or transcript but it is in trans-Atlantic, transnational and trans-sexual.
The same contrast is seen with some prefixes of Greek origin (see 90. The Greek Impact on English Vocabulary):
Anti (“against”) is not a prefix in antigen or antipathy, but it is in anti-clockwise, anticyclone, antitank and anti-war.
Hyper (“above”) is not a prefix in hyperbole, but it is in hyper-market, hypersensitive and hypertext.
Words whose meaning includes the idea of “not” do not have to have a prefix (see 13. Hidden Negatives, and words with -less in 106. Word-Like Suffixes). However, many do. The main prefixes meaning “not” may be illustrated as follows:
un-American, unbelief, unbending, unbroken, uncomplaining, unfailing, uninspiring, unelected, unexplained, unhappy, unhelpful, unprofessional, unrest, unsuitable, untrue, unwilling(ness), unwise
disarray, disbelieving, dishonest, disinterested, disorderly, disproportionate, disregard, dissatisfied, distasteful
non-believable, non-conformist, non-member, non-native, non-negotiable, non-payment, non-professional, non-refundable, non-smoker, non-stop, non-playing, non-standing, non-selected
illegitimate, illogical, immovable, imperfect, impervious, impractical, inadvisable, incapable, inequality, inexplicable, inhuman(ity), inimitable, irreplaceable
Comprehensive overviews of these prefixes are easily obtainable elsewhere and are not the aim here. The following points seem of especial interest.
Un- is commonly added to adjectives and participles, sometimes to nouns (underlined above). Although it is also found with verbs, its meaning there is mostly “reverse” rather than “not” (uncover, undress, undo, untie).
Dis- has to be distinguished from the similarly-spelt Latin prefix meaning “widely” (in words like disseminate and dispel). Like un-, it can mean “reverse” as well as “not”, particularly in verbs, e.g. disappear, disarm, discharge, discredit and disembark. With the not meaning, it seems at first sight to be especially common with adjectives (only disarray above is not one). However, adjectives with dis- usually seem able to become nouns as well: disbelief, dishonesty, disorder, disregard, dissatisfaction, distaste.
Disbelief and unbelief reflect two different meanings of BELIEVE: the former “strongly doubting the truth of a statement or situation”, the latter “not accepting a religious system or idea”. Similarly, disinterested and uninterested both exist, respectively meaning “not involved” and “not interested”.
Non- very often has a hyphen. Like un-, it is mostly combined with nouns, adjectives and participles. With nouns, it can express absence from a group (non-member, non-professional, non-smoker). Participles with non- (underlined above) seem less common than those with un-, but are still quite numerous.
With adjectives, non- is sometimes used instead of un- to avoid a subjective judgment: an unprofessional footballer is a professional one failing to behave as required, while a non-professional footballer is just not a professional one. An unbelievable story is amazing or extremely good/bad, whereas a non-believable story is simply one that cannot be believed (see 114. Tricky Word Contrasts 3, #7).
In- goes mainly with adjectives and nouns. The “n” changes to mirror a following “l”, “m”, or “r”, and becomes “m” before “p”. Words to which in- can be added seem rather unpredictable. The adjectives of inability and inequality, for example, are unable and unequal, while inexplicable exists alongside unexplained.
In addition to the main negative prefixes, a number of others are worth noting. De- (pronounced /di:/ more often than /dɪ/) is like un- and dis- in expressing reversal, but mainly the kind where something is removed. Thus descale means “remove limescale” and decontaminate “remove contamination”. Other examples are debrief, decode, dehydrate, deindustrialise, demerge, demobilise, demotivate, depopulate and de-skill.
Some words of Greek origin are made negative through the addition of the Greek prefix a-. Examples include amorphous, apathetic, apolitical, asexual, atheist and atypical.
Finally, two negative prefixes that mean “badly” rather than “not” are mis- and ill-. The former exists in such words as misbehave, misconduct, misdemeanour, misfire, misfit, misinterpret, misrepresent, mistake, mistreat, mistype and misunderstand. Mis- seems typical of verbs and the nouns derived from them, plus a few other nouns (underlined).
Ill- must not be confused with the il-l made by changing in- into il-. Examples are ill-advised, ill-bred, ill-fitting, ill-represented, ill-timed, ill-treat and ill-use. Most, it will be observed, involve participles. The verb ill-treat seems to imply more cruelty than mistreat.
1. Latin and Greek Borrowings
Ex- (“out of” in Latin) often means “former”, as in ex-member, ex-president and ex-wife. Semi-, Latin for “half”, is found in words like semi-conscious, semi-final and semi-professional. Multi- (“many” in Latin) exists in multi-coloured, multi-cultural, multi-lingual and multi-talented (for a note on pronunciation, see 86. The Pronunciation of “e” and “i”).
Greek borrowings include pseudo- (meaning “fake”), established in words like pseudonym and pseudo-intellectual and able to create new words like pseudo-expert. Auto- (“self” in Greek) exists in such words as autobiography, automatic, automobile and autopilot.
2. “En-” and “Mid-”
These two English prefixes tend respectively to make verbs and nouns. Verbs with en- (broadly = “into”) include empower, enable, enact, encamp, encode, endanger, endear, enforce, engulf, enlarge, enlighten, enrich, enthrone, entitle, entrust and envision. The partner word may be a noun, verb or adjective (underlined). Adjectives combine with en- less commonly than with the corresponding suffix -en, as in blacken and widen.
Nouns with mid- (“middle”) include mid-life, midnight, mid-sentence, mid-20s, mid-term and midwinter. Most can also be used as adjectives.
3. Word-Like Prefixes
Some spellings seem best treated as prefixes even though they lack one or more of the four normal characteristics listed above. Among these are spellings that also form ordinary words by themselves (similar to suffixes that do the same: see 106. Word-Like Suffixes).
One important group resembles prepositions. Interestingly, the prepositions they resemble are practically the same ones that can also be used alone after BE (see 154. Lone Prepositions after BE). As prefixes they also resemble the first parts of nouns made from phrasal verbs (input, outbreak, upturn etc. – see 139. Phrasal Verbs). However, these latter may be better thought of as roots rather than prefixes, since they have a clear derivational link to two-word verbs. Examples of preposition-like prefixes are:
downbeat, downhearted, downside, downstairs
in-demand, in-form, in-house
offhand, off-licence, off-limits, offline, offroad, offscreen, offside
on-line, onscreen, onshore
over-burden, over-emphasise, overpopulated, over-zealous (= “excessively”)
overarching, overcoat, overhang, overhead, overthrow
outdo, outlast, outperform, outplay, outrun, outsell, outsmart, outthink, outwit (out- is always said without stress and means “better”)
outfit, outline, outmoded, outworn
underachieving, underestimate, undernourished (= “insufficiently”)
upbeat, upcountry, update, uphill, uphold, upstairs
Also notable are self- and half-. Examples with the former include self-assurance, self-catering, self-confidence, self-contained, self-control, self-defence, self-governing, self-made, self-righteous and self-service. Examples with the latter include half-baked, half-hearted, half-kilo and halftime.