Words That Start with UN-: Prefix Guide with Examples

The prefix un- is one of the most versatile tools in English. Attach it to an adjective and you get the opposite: happy → unhappy. Attach it to a verb and you reverse the action: do → undo, lock → unlock. It always adds exactly 1 syllable, it works with hundreds of base words, and it's one of the first prefixes children learn.

What UN- Means

The prefix un- carries two distinct meanings:

"Not" or "opposite of" — when attached to adjectives and some nouns:

• happy → unhappy (not happy)
• fair → unfair (not fair)
• kind → unkind (not kind)
• usual → unusual (not usual)

"Reverse of" or "undo" — when attached to verbs:

• do → undo (reverse doing)
• lock → unlock (reverse locking)
• fold → unfold (reverse folding)
• wrap → unwrap (reverse wrapping)

This dual function makes un- extremely productive. You can negate almost any adjective and reverse almost any verb simply by adding these two letters.

How UN- Affects Syllable Count

The prefix un- is always 1 syllable and always adds exactly 1 syllable to the base word:

Base Word	Base Syllables	UN- Word	Total Syllables
happy	2	unhappy	3
fair	1	unfair	2
kind	1	unkind	2
able	2	unable	3
aware	2	unaware	3
do	1	undo	2
lock	1	unlock	2
cover	2	uncover	3
comfortable	3-4	uncomfortable	4-5

The addition is always clean — the base word keeps its original pronunciation and syllable count, and "un" sits in front as a separate syllable. See our prefixes and suffixes guide for more on how prefixes work.

UN- + Adjectives

This is the most common use of un-. Here are examples organized by the syllable count of the resulting word:

Two-Syllable UN- Words (base = 1 syllable)

Unclear, unclean, uncool, undone, unfair, unfit, unfold, unkind, unlike, unreal, unrest, unsafe, unsure, untrue, unwell, unwise.

Three-Syllable UN- Words (base = 2 syllables)

Unable, unhappy, unaware, unbroken, uncertain, uncommon, uneasy, unequal, uneven, unfairy... wait — unfairly? That's un- + fair + -ly. Let me stick with un- + adjective:

Unable, unhappy, unaware, unbroken, uncertain, uncommon, uneasy, unequal, uneven, unfriendly, ungrateful (4? un·grate·ful = 3), unhealthy, unlikely, unlucky, unpleasant, unsteady, untidy, unusual, unwilling, unworthy.

Four-Syllable UN- Words (base = 3 syllables)

Unavoidable (5 — too many), unbearable (4: un·bear·a·ble), unbelievable (5), uncomfortable (4-5), unconventional (5), undesirable (5), uneducated (5), unforgettable (5), unfortunate (4: un·for·tu·nate), unnecessary (5), unorganized (4: un·or·ga·nized), unpredictable (5), unreasonable (5), unrecognizable (6).

Verified 4-syllable un- words: unfortunate, unorganized, unattractive, unacceptable... wait, un·ac·cep·ta·ble = 5. Let me be careful:

un·for·tu·nate = 4. Yes. un·com·for·ta·ble = 5 (careful) or 4 (casual).

UN- + Verbs

When un- attaches to verbs, it means "reverse the action":

Verb	UN- Verb	Meaning
do	undo	Reverse doing
lock	unlock	Open a lock
fold	unfold	Open something folded
wrap	unwrap	Remove wrapping
tie	untie	Remove a tie/knot
zip	unzip	Open a zipper
plug	unplug	Remove from outlet
pack	unpack	Remove from container
load	unload	Remove a load
cover	uncover	Remove a covering
dress	undress	Remove clothing
hook	unhook	Remove from a hook
cork	uncork	Remove a cork
roll	unroll	Reverse rolling
wind	unwind	Reverse winding
mask	unmask	Remove a mask
chain	unchain	Remove chains

Each un- verb has exactly 1 more syllable than the base verb. Browse our words starting with un- page for the complete searchable list.

UN- + Nouns (Less Common)

Un- occasionally attaches to nouns, though this is rarer:

Noun	UN- Noun	Meaning
rest	unrest	Lack of peace
truth	untruth	A falsehood
ease	unease	Discomfort

These noun uses are limited compared to the adjective and verb uses.

The Difference Between UN- and NON-

Both un- and non- can mean "not," but they're not interchangeable:

Un- implies a judgment or carries emotional weight. "Unhappy" suggests distress. "Unfair" implies injustice. "Unusual" often implies surprise or interest.

Non- is neutral and clinical. "Nonfiction" simply means "not fiction." "Nonsmoking" is a factual category. "Nonexistent" is a neutral observation.

Compare: "He's an unscientific person" (he rejects or ignores science — a criticism) vs. "It's a nonscientific topic" (it's simply not related to science — neutral).

Un- adds 1 syllable. Non- also adds 1 syllable. The syllable math is the same, but the meaning differs.

Tricky UN- Words Where UN- Isn't a Prefix

Some words start with the letters U-N but don't use un- as a prefix. The "un" is just part of the root word:

Word	Why It's Not UN-
uncle	From Latin "avunculus" — "un" is part of the root
under	Old English compound — "un" isn't a prefix here
until	"Un" + "til" (an old word meaning "to") — but not the negating prefix
understand	"Under" + "stand" — compound, not prefixed
universe	From Latin "universus" — "uni" means "one"
union	From Latin "unio" — "uni" means "one"
unit	From Latin "unitas" — "uni" means "one"
uniform	"Uni" (one) + "form" — different prefix
unique	From Latin "unicus" — "uni" means "one"
united	From Latin "unitus" — "uni" means "one"

The test: can you remove "un-" and still have a real base word? "Unhappy" → "happy" (yes, it's a prefix). "Uncle" → "cle" (no, it's not a prefix).

UN- Words in Word Games

For Scrabble and Words With Friends, un- words are strategically useful. Adding "un" to the front of an existing word on the board can score points in multiple directions.

Common short un- words useful in word games:

Word	Scrabble Score
undo	5
unit	4
unto	4
unfit	8
untie	5
unzip	16
unbox	14

Use our syllable counting tool to verify syllable counts for any un- word.

Frequently Asked Questions

How many syllables does UN- add?

The prefix un- always adds exactly 1 syllable. Happy (2) → unhappy (3). Lock (1) → unlock (2). The rule has no exceptions.

What's the difference between UN- and DIS-?

Both can mean "not" or "reverse," but they attach to different words. Un- works with most adjectives (unhappy, unfair) and many verbs (undo, unlock). Dis- works with a different set: disagree, disappear, disconnect, dislike. Some words accept both: "uninterested" (not interested) and "disinterested" (impartial) have different meanings.

Is "uncle" an UN- word?

No. "Uncle" comes from Latin "avunculus" — the "un" is part of the root word, not a prefix. You can't remove "un-" and get a meaningful base word ("cle" isn't a word).

Can you add UN- to any adjective?

Most adjectives accept un-, but not all. Some adjectives already have established negative forms using other prefixes: "impossible" (not "unpossible"), "illegal" (not "unlegal"), "irregular" (not "unregular"). These use Latin-origin prefixes (im-, il-, ir-) because the base words have Latin origins.

How many words start with UN- in English?

English has over 3,000 words beginning with un-, making it one of the most productive prefixes in the language. Browse our words starting with un- page for a searchable list.