English Root Words, Prefixes & Suffixes: A Practical Map

Most long English words are built from three kinds of parts: a prefix at the front, a root in the middle and a suffix at the end. Learn what the most common parts mean and you can make an educated guess at words you have never seen: in + cred + ible means "not believable", and bene + vol + ent means "wishing well". The tables below map the highest-value prefixes, Latin roots, Greek roots and suffixes, then show the spelling changes and false matches that trip people up.

Use this page as a reference. Scan a table when you meet an unfamiliar word, or work through one table a week and collect three example words for each part.

How an English word is put together

Take the word unbreakable. Break is the base, a word that can stand on its own. The prefix un- adds "not" and the suffix -able adds "can be". Now take interruption. The core is rupt, from the Latin for "break", which cannot stand alone in English. The prefix inter- means "between" and the suffix -ion turns the verb into a noun. Same meaning of break, two different routes.

That split matters because the two layers behave differently:

• Base words are native or fully naturalized English: help, kind, work, happy. Affixes on them are usually transparent (helpful, unkind, rework, happiness).
• Bound roots arrived from Latin, directly or through French, or from Greek: rupt, spect, dict, graph, chron. They carry most of the academic, legal, medical and scientific vocabulary that makes reading hard.

Prefixes mostly change meaning (legal becomes illegal). Suffixes mostly change word class (legal becomes legalize, legality, legally). If you can spot both ends, the root in the middle is usually short enough to recognize.

The high-frequency prefixes

These prefixes appear across everyday and academic English. The first four (un-, re-, in- and dis-) are the ones you will meet most often.

Number prefixes are worth learning as a set, because they recur in science, music and geometry: uni- (one: unicycle), mono- (one: monologue), bi- (two: bicycle), di- (two: dioxide), tri- (three: triangle), quad- or quadr- (four: quadrilateral), tetra- (four: tetrahedron), pent- or penta- (five: pentagon), dec- or deca- (ten: decade), cent- (hundred: century), milli- (thousandth: millimeter) and kilo- (thousand: kilogram).

Latin roots that open the most doors

Latin reached English both directly, through scholars and scientists, and indirectly, through the French spoken by England's rulers after 1066. That double route is why one Latin root often has two spellings in English (duc and duct, mit and miss, vid and vis).

Notice how often the same prefix recombines with different roots. Con- appears in conduct, convert, construct, convene and contradict; de- appears in deduct, describe and deport. Once you know ten prefixes and ten roots, you have the parts for dozens of words. For deeper practice lists, see our pages on Latin roots and root words.

Greek roots for science, medicine and ideas

Greek parts dominate scientific and technical vocabulary, and they often combine with each other rather than with English words: bio + graph + y, tele + phone, micro + scope.

Greek roots stack neatly. Philanthropy is phil (love) + anthrop (human) + -y: love of humankind, which is why it came to mean charitable giving. Misanthrope swaps in miso- or mis-, from Greek misein (to hate, and unrelated to the English prefix mis- meaning wrongly), for someone who dislikes people. Our Greek roots page collects more families like these.

Suffixes: what they tell you about a word

Suffixes rarely change the core meaning. Instead they tell you what job the word does in a sentence, which is often enough to parse a hard sentence even when the root is unfamiliar.

Suffixes can also move the stress of a word, which is useful for pronunciation. Listen to the stressed syllable move to the right in PHO-to-graph, pho-TO-gra-pher and pho-to-GRAPH-ic.

Spelling changes that hide familiar parts

Latin prefixes often changed their last letter to match the first letter of the root. This is called assimilation, and it disguises prefixes you already know.

The doubled consonant is the clue. When you see acc-, aff-, all-, app-, att-, coll-, corr-, ill-, imm- or irr- at the start of a word, there is probably an assimilated prefix, and the root begins after the double letter: ac + cept, col + lect, ir + regular.

Traps: when the parts mislead you

Roots are a guide, not a guarantee. These are the classic false matches.

• Inflammable means easily set on fire, just like flammable. The in- is Latin for "into", not the negative in-. Invaluable is similar: it means so valuable that no price can be put on it, not worthless.
• Two roots can look the same. Latin ped means foot (pedal, pedestrian, pedicure), but Greek paed or ped means child (pediatrics, encyclopedia, pedagogy). A pediatrician treats children, not feet.
• Some letters are not a prefix at all. The re in reindeer is not re- (again); the word comes from Old Norse. The un in uncle, union and unique is not un- (not); union and unique come from Latin unus (one).
• Meaning drifts. Decimate originally referred to killing one soldier in ten, but in most modern usage it means destroying a large part of something. Restive once meant stubbornly standing still (rest + -ive) and now usually means restless or unruly.
• One root, several meanings. Path means both feeling (empathy, sympathy) and disease (pathology, psychopath), because the Greek word covered suffering and experience.

Decoding hard words, step by step

Here is the process on five words that appear in advanced reading and test prep:

The method is the same each time: strip the suffix to find the word class, strip the prefix to find the direction or negation, name the root, then reassemble and check the result against the sentence. Benevolent and malediction also show a useful pair: bene (well) and mal or male (badly) appear in benefit and malfunction, benefactor and malefactor, benign and malign.

Practice exercises

Word-family grid. Pick one root from each table and list every word you can think of that contains it. For port, you might reach transport, export, import, report, support, portable, porter and deport. Then check each in a dictionary; you will find a few where port has a different origin, such as port meaning harbor, which comes from Latin portus rather than portare (to carry).

Prefix swaps. Keep the root and change the prefix: inject, eject, reject, project, subject, object. Write one sentence for each and notice how the prefix sets the direction of the throw.

Reverse decoding. Cover the "Actual meaning" column in the decoding table, work out each word from its parts, then compare. Repeat with words from your own reading.

Build from parts. Combine prefixes, roots and suffixes from the tables into real words and check them: re + ject + ion, trans + port + able, in + vis + ible. WordFren's Word Forge game is built on this idea, asking you to assemble words from roots, and our vocabulary games page lists other game formats that train the same skill.

If you are preparing for the SAT, GRE or TOEFL, the root families in our GRE and TOEFL root families guide go further into test-specific words, and the prefixes and suffixes vocabulary page gives more example words to practice with.