Word Formation Reference
How English builds new words: prefixes change meaning, suffixes change word class — and word class starts with the 8 parts of speech.
👤 The 8 Parts of Speech
Every English word belongs to one of these eight categories, based on the job it does in a sentence. The suffixes below often signal which one.
Noun
Names a person, place, thing, or idea
dog, London, happiness
Verb
Expresses an action or state
run, is, think
Adjective
Describes a noun
red car, quick fox
Adverb
Describes a verb, adjective, or another adverb — often how/when/where
quickly, very, here
Pronoun
Replaces a noun
she, it, her, this
Preposition
Shows the relationship between words (place, time, direction)
on, under, since
Conjunction
Connects words, phrases, or clauses
and, because, but
Interjection
Expresses sudden emotion, stands alone
Wow!, Ouch!, Hey!
Anatomy of a word
un
help
ful
Prefix (meaning)
Root (base)
Suffix (word class)
🔵 Noun Suffixes
-tion / -sion
Action or result
educate → education
decide → decision
inform → information
-ment
Action or result
develop → development
agree → agreement
achieve → achievement
-ness
State or quality (from adj)
happy → happiness
dark → darkness
kind → kindness
-er / -or
Person who does
teach → teacher
act → actor
drive → driver
-ity / -ty
Quality (from adj)
creative → creativity
able → ability
real → reality
-ance / -ence
State or action
perform → performance
differ → difference
exist → existence
🟢 Adjective Suffixes
-ful
Full of / having
care → careful
beauty → beautiful
help → helpful
-less
Without
care → careless
home → homeless
use → useless
-ous / -ious
Having quality of
danger → dangerous
ambition → ambitious
fame → famous
-able / -ible
Can be done
comfort → comfortable
flex → flexible
rely → reliable
-ive
Tendency to
create → creative
act → active
attract → attractive
-al / -ial
Related to
nation → national
finance → financial
culture → cultural
🔴 Negative Prefixes
un-
Not / opposite (most common)
happy → unhappy
able → unable
fair → unfair
in- / im- / il- / ir-
Not (before specific letters)
incorrect (c,d,f)
impossible (m,p)
illegal (l)
irregular (r)
dis-
Opposite / reversal
disagree
disappear
dishonest
mis-
Wrongly / badly
misunderstand
mislead
misbehave
🔸 Other Useful Prefixes
re-
Again
write → rewrite
do → redo
build → rebuild
over-
Too much
overwork
overeat
oversleep
under-
Too little / below
underestimate
underpaid
undercooked
pre- / post-
Before / After
preview
postpone
pre-war
🔄 Word Family Examples