What Are Prefixes? Definition and Examples

A prefix is a group of letters added to the beginning of a word (the root or base word) to change its meaning. Understanding prefixes can help you decode unfamiliar words, build your vocabulary, and recognize patterns in English spelling and word formation.

Key Points About Prefixes:

• A prefix cannot stand alone as a word on its own.
• Adding a prefix to a base word usually changes its meaning in a predictable way.
• Most prefixes come from Latin or Greek origins.
• Prefixes generally do not alter the word’s part of speech, but they do modify its meaning.

Example:

• Base word: “happy”
• Adding the prefix “un-” → “unhappy” (meaning: not happy)

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How Prefixes Change Meaning

By adding a prefix, you can:

• Negate or show the opposite of a base word (e.g., “un-” turns “kind” into “unkind,” meaning not kind).
• Show repetition or intensification (e.g., “re-” in “redo” means do again).
• Indicate position or direction (e.g., “sub-” in “submarine” means under the water).
• Indicate quantity or number (e.g., “tri-” in “triangle” indicates three sides).
• Show time or order (e.g., “pre-” in “preview” means before viewing).

Common English Prefixes and Their Meanings

Below is a list of many common English prefixes, their basic meanings, and examples of words formed with them. Note that some prefixes can have slightly different nuances depending on the root word they are attached to.

1. Negation or Opposition Prefixes

1. un-: means “not” or “opposite of”
   • Examples: unhappy (not happy), unfair (not fair), unlocked (not locked), unusual (not usual)
2. in-/im-/il-/ir-: mean “not” (the form depends on the first letter of the base word)
   • in-: inactive (not active), indirect (not direct)
   • im-: impossible (not possible), immature (not mature)
   • il-: illegal (not legal), illogical (not logical)
   • ir-: irregular (not regular), irrelevant (not relevant)
3. dis-: means “not” or “opposite of,” also can indicate removal
   • Examples: disagree (not agree), disappear (go away), disconnect (detach), dishonest (not honest)
4. non-: means “not”
   • Examples: nonstop (without stopping), nonfiction (not fiction), nonverbal (not verbal)
5. mis-: means “wrong” or “incorrectly”
   • Examples: misunderstand (understand incorrectly), misuse (use incorrectly), misbehave (behave badly)

2. Time, Order, and Position Prefixes

1. pre-: means “before”
   • Examples: preview (view before), predict (say before it happens), preheat (heat beforehand)
2. post-: means “after”
   • Examples: postwar (after the war), postscript (written after the main text), postpartum (after giving birth)
3. fore-: means “before” or “front”
   • Examples: forecast (predict beforehand), forehead (front part of the head), forewarn (warn before)
4. re-: means “again” or “back”
   • Examples: redo (do again), return (come back), rewrite (write again), replay (play again)
5. ex-: means “out,” “from,” or “former”
   • Examples: extract (pull out), ex-president (former president), exterior (outer part)
6. sub-: means “under” or “below”
   • Examples: submarine (underwater vessel), substitute (place under or instead), subterranean (under the earth)
7. inter-: means “between” or “among”
   • Examples: international (between nations), interact (act between or among), internet (network between networks)
8. intra-/intro-: means “within” or “inside”
   • Examples: intranet (network within an organization), intravenous (within a vein), introduce (lead into)
9. trans-: means “across” or “through”
   • Examples: transport (carry across), translate (carry meaning across languages), transform (change through)
10. tele-: means “far” or “distance”
    • Examples: telephone (sound over distance), television (vision over distance), teleport (carry over distance)

3. Number and Quantity Prefixes

1. mono-/uni-: means “one” or “single”
   • mono: monologue (speech by one person), monochrome (one color)
   • uni: unicycle (cycle with one wheel), uniform (one form), unique (one of a kind)
2. bi-/di-: means “two”
   • bi: bicycle (two wheels), bilateral (involving two sides)
   • di: dichotomy (division into two parts), dioxide (two oxygen atoms)
3. tri-: means “three”
   • Examples: triangle (three angles), tricycle (three wheels), trilogy (set of three works)
4. multi-/poly-: mean “many”
   • multi: multicultural (pertaining to many cultures), multimedia (multiple media)
   • poly: polygon (many angles), polyglot (one who speaks many languages)
5. semi-/hemi-/demi-: mean “half” or “partly”
   • semi: semicircle (half circle), semifinal (the round before the final)
   • hemi: hemisphere (half of a sphere, e.g. Northern Hemisphere)
   • demi: demigod (half-god, partially divine)

4. Size, Intensity, and Degree Prefixes

1. mini-: means “small”
   • Examples: minibus (small bus), miniskirt (short skirt), miniature (small version)
2. micro-: means “very small” or “one-millionth” (in metric units)
   • Examples: microscope (instrument to see small things), microchip (very small chip), microbiology (study of small life forms)
3. macro-: means “large,” “long,” or “big picture”
   • Examples: macroeconomics (large-scale economics), macrocosm (large universe), macroscopic (visible to the naked eye)
4. hyper-: means “over,” “excessive,” or “beyond normal”
   • Examples: hyperactive (overly active), hypertension (high blood pressure), hyperlink (beyond a normal link)
5. super-/sur-: means “above,” “beyond,” or “over”
   • Examples: superstar (above a regular star), superhuman (beyond human), surplus (over what is needed)
6. ultra-: means “extremely” or “beyond”
   • Examples: ultrasonic (beyond normal sound range), ultramodern (extremely modern), ultraviolet (beyond violet in spectrum)

5. Quality, Manner, and Other Miscellaneous Prefixes

1. pro-: can mean “forward,” “in favor of,” or “before”
   • Examples: progress (step forward), propose (put forward), proactive (acting before a situation arises)
2. anti-: means “against” or “opposite”
   • Examples: antibiotic (against life of bacteria), antisocial (against social norms), antidote (remedy against poison)
3. de-: can mean “down,” “remove,” or reverse the action
   • Examples: descend (go down), decode (remove code or interpret), devalue (reduce value)
4. counter-: means “against” or “opposite”
   • Examples: counteract (act against), counterattack (attack in response or against), counterclockwise (opposite direction of clock)
5. co-/com-/con-/col-/cor-: means “with” or “together”
   • co: coexist (exist together), coauthor (author together)
   • com-/con-/col-/cor- (varies by the following letter): combine, connect, collaborate, correspond
6. en-/em-: means “cause to be,” “put into,” or “make”
   • Examples: enable (make able), empower (give power), enclose (put inside)

Tips for Using Prefixes

1. Spelling Adjustments:
   Some prefixes change form slightly depending on the first letter of the root word (e.g., in- becomes im- before words starting with m or p).
2. No Hyphen Needed (Usually):
   Most prefixes don’t need a hyphen when attached to a root word, but check a dictionary when in doubt (e.g., “cooperate” often appears as “co-operate” in some styles).
3. Consistent Meaning:
   While most prefixes have relatively consistent meanings, context matters. Some words have become so well-established that the prefix meaning is not as obvious (e.g., “understand” does not literally mean “stand under”).
4. Building Vocabulary:
   Recognizing prefixes helps you guess meanings of unfamiliar words. For instance, if you know “anti-” means “against” and you encounter “antithesis,” you might infer it has something to do with opposition or contrast.

Additional Word Examples by Prefix

• un-: unreal, undo, unearth, unwell
• re-: reconsider, rebuild, return, refresh
• dis-: dislike, disappear, disapprove, disconnect
• pre-: prehistoric, predate, preschool, prepare
• post-: postgraduate, postmortem, postpone, postscript
• sub-: subway, substitute, submerge, subparagraph
• inter-: international, interact, intermission, interchangeable
• multi-: multimillionaire, multimedia, multilateral, multitask
• co-: coexist, cooperate, coordinate, coworker
• de-: defrost, deactivate, degrade, depart
• anti-: antithesis, antibody, antifreeze, antibiotic
• trans-: translate, transport, transform, transcontinental

Prefixes are powerful linguistic tools that allow English speakers and writers to alter meanings, indicate negation, show repetition, express quantities, or convey relationships in time, space, and manner. By learning common prefixes and their meanings, you can greatly expand your vocabulary, improve reading comprehension, and become more adept at both understanding and creating new words.