An affix is a word part attached to a root word to create a new word with a different meaning or grammatical function.
Prefix — added to the beginning of a root word: un + happy = unhappy
Suffix — added to the end of a root word: hope + less = hopeless
Root word — the base word that carries the core meaning
Understanding affixes is one of the most powerful vocabulary-building skills. If you recognise common prefixes and suffixes, you can decode thousands of unfamiliar words — even ones you have never seen before.
Key Terms
Term
Meaning
Affix
A word part added to a root (prefix or suffix)
Prefix
An affix added to the beginning of a word
Suffix
An affix added to the end of a word
Root word
The base word to which affixes are attached
Morpheme
The smallest unit of meaning in a word
Common Prefixes
Prefix
Meaning
Examples
un-
not / opposite of
unhappy, unlock, unfair
re-
again
rewrite, replay, rebuild
pre-
before
preview, prehistoric, precaution
mis-
wrongly or badly
misunderstand, misspell, mislead
in- / im- / ir-
not
incorrect, impossible, irregular
dis-
not / reverse
disagree, disconnect, disappear
inter-
between / among
international, interact, intervene
sub-
under / below
submarine, subtitle, substandard
over-
too much
overeat, overreact, overwhelm
under-
too little / below
underestimate, undermine, underline
super-
above / beyond
supermarket, superhero, supernatural
anti-
against
antibiotic, antisocial, anticlockwise
auto-
self
autobiography, automatic, autograph
bi-
two
bicycle, bilingual, biweekly
trans-
across
transport, translate, transfer
Common Suffixes
Noun Suffixes
Suffix
Meaning
Examples
-ness
state or quality of
happiness, darkness, kindness
-tion / -sion
action or process
education, decision, expression
-er / -or
one who does
teacher, actor, writer
-ment
result or state of
enjoyment, government, agreement
-ity
quality or state
equality, creativity, reality
-ism
doctrine or practice
capitalism, realism, journalism
-ist
one who practises
artist, scientist, journalist
Adjective Suffixes
Suffix
Meaning
Examples
-ful
full of
careful, hopeful, peaceful
-less
without
careless, hopeless, harmless
-able / -ible
can be done
readable, flexible, breakable
-ous
having the quality of
dangerous, famous, gorgeous
-ic
relating to
scientific, historic, academic
-al
relating to
musical, logical, natural
Adverb and Verb Suffixes
Suffix
Use
Examples
-ly
forms adverbs from adjectives
quickly, happily, carefully
-ise / -ize
forms verbs
organise, realise, minimise
-en
forms verbs from adjectives
darken, brighten, strengthen
How Affixes Change Word Class
Affixes can transform one part of speech into another:
Root (verb)
+ Suffix
New word (noun)
educate
+ -tion
education
enjoy
+ -ment
enjoyment
create
+ -ivity
creativity
Root (adjective)
+ Suffix
New word (noun)
happy
+ -ness
happiness
equal
+ -ity
equality
Root (noun/adjective)
+ Suffix
New word (adverb)
quick
+ -ly
quickly
careful
+ -ly
carefully
Decoding Unfamiliar Words
When you encounter an unfamiliar word, break it into parts:
Example:irresponsible
ir- = not
responsible = accountable, trustworthy
-ible = able to be done
Meaning: not capable of being responsible; lacking accountability
Example:autobiography
auto- = self
bio = life
-graphy = writing
Meaning: writing about one's own life
Spelling Rules When Adding Affixes
Drop the final 'e' before a suffix beginning with a vowel: hope → hoping, love → lovable
Keep the final 'e' before a suffix beginning with a consonant: hope → hopeful, care → careless
Double the final consonant in short words ending in consonant-vowel-consonant before adding a vowel suffix: run → running, sit → sitting
Change 'y' to 'i' before most suffixes: happy → happiness, carry → carried
Common Mistakes
Confusing similar prefixes:un- and in- both mean "not," but you cannot swap them freely: it is unhappy (not inhappy) and incorrect (not uncorrect). The correct prefix must be learned for each word.
Spelling errors when adding suffixes: Remember the spelling rules above, especially the double-consonant rule (running, not runing).
Guessing root meaning incorrectly: The prefix dis- in discover does not mean "not" — it means "to uncover or reveal." Not every word that looks like it has a prefix actually does.
Tips and Tricks
Learn prefixes in meaning groups: all the "not" prefixes together (un-, in-, im-, ir-, dis-), all the "again" prefixes together.
When you learn a new word, immediately identify its root, prefix, and suffix to build your understanding.
Create word webs: start with a root (create) and map out all the related words (creator, creation, creative, creativity, recreate, uncreative).
Use a dictionary to check which prefix is correct for a specific word — do not assume they are interchangeable.