How Prefixes and Suffixes Build New Words

Most long English words are not really long at all. They are short words with pieces attached. Unbelievable is believe with un- at the front and -able at the back. Once you can see those pieces, unfamiliar words become easier to understand, easier to spell and, for word-game players, easier to find on a rack.

Roots, prefixes and suffixes

Every word has a root or base that carries its core meaning. Prefixes and suffixes are affixes, extra parts attached to the base.

A word can carry more than one prefix or suffix: un-break-able, re-organ-ize-ation.

Common prefixes and what they mean

The "not" prefixes are worth a closer look. In- becomes im- before B, M and P (imbalance, immature, impossible), il- before L (illegal) and ir- before R (irregular). That is why so many of these words have a double letter: il + legal, ir + regular, im + mature.

Common suffixes and what they do

Suffixes often tell you the part of speech of the new word.

Spelling rules for suffixes

Prefixes rarely change spelling, but suffixes do. Four rules cover most cases.

1. Drop the silent E before a vowel suffix

make → making, hope → hoping, love → lovable. Keep the E before a consonant suffix: hope → hopeful, care → careless. Exceptions keep a soft C or G sound: noticeable, changeable, courageous.

2. Change Y to I

When a word ends in a consonant plus Y, change the Y to I before most suffixes: happy → happiness, carry → carried, beauty → beautiful. Keep the Y before -ing: carrying, studying.

3. Double the final consonant

For short words ending in one vowel plus one consonant, double the consonant before a vowel suffix: stop → stopped, run → running, big → biggest. For longer words, double only if the stress is on the last syllable: begin → beginning, occur → occurred, but visit → visited.

4. Just add the prefix

Do not drop letters when you add a prefix: dis + satisfied = dissatisfied, un + necessary = unnecessary, mis + spell = misspell. These double letters are some of the most common spelling mistakes; see our misspellings library for more.

Why this matters in word games

Prefixes and suffixes are the reason a small word can grow into a big score. In Scrabble and Words With Friends, adding RE-, UN-, -ED, -ER or -ING to a word already on the board is one of the most common ways to make a play. Players call these additions hooks and extensions.

• PLAY becomes REPLAY, PLAYED, PLAYER, PLAYING.
• DO becomes UNDO, REDO, OVERDO.

Knowing which affixes a word accepts is valuable because not every combination is a real word. Unhappy is fine, but unsad is not in standard dictionaries. When in doubt, check with the word checker, or browse lists of words that start with RE and words that end in ING.

Study the most useful affixes

Use the flashcards to learn fourteen of the most common prefixes and suffixes. Try to give the meaning and two example words before you flip each card.

Practice quiz