Letters and spelling

Words with the un- prefix

This list gathers common words formed with the prefix un-, which flips a word's meaning to its opposite or means not, as in unhappy or unable. It helps students studying prefixes, ESL learners building vocabulary, and writers looking for a quick negative form of a familiar word. Cover the un- on each word and see if you still recognize the base word underneath.

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Words with the un- prefix

Word	Meaning	In a sentence
unhappyadjective	Feeling or clearly showing a sense of sadness or dissatisfaction.	He looked visibly unhappy after hearing his disappointing exam results.
unableadjective	Not having the necessary skill, strength, resources, or opportunity to do something.	He was unable to finish the race after twisting his ankle.
unfairadjective	Not fair, just, or right; treating people unequally or without reasonable cause.	It felt unfair that only one team was penalized for the same mistake.
unkindadjective	Not kind; showing a lack of care or consideration for others' feelings.	It was unkind of him to laugh at her mistake in front of everyone.
unclearadjective	Not easy to understand, see, or interpret; not clearly stated or explained.	The instructions were unclear, so several students made the same mistake.
unusualadjective	Not common or ordinary; different from what is expected or typical.	It's unusual for him to arrive late; something must have happened.
uncertainadjective	Not known, decided, or definite; lacking confidence or clear information.	The outcome of the negotiations remains uncertain at this stage.
unawareadjective	Not knowing about or noticing a particular fact or situation.	She was completely unaware that her flight had been delayed.
uncomfortableadjective	Causing or experiencing physical unease, such as pain or awkward pressure, rather than ease.	The wooden chair grew uncomfortable after we had been sitting on it for over an hour.
undoverb	To reverse or cancel an action, or to unfasten something that was tied or done up.	Click this button to undo your last change in the document.
unequaladjective	Not equal in size, amount, or value, or, in the case of a contest, heavily one-sided.	The two candidates ran an unequal race with vastly different budgets.
unfoldverb	To open out something that was folded, or to gradually reveal or develop over time.	She unfolded the map to find the quickest route to the coast.
unfortunateadjective	Having or marked by bad luck; regrettable or unlucky.	It was unfortunate that the picnic was ruined by sudden rain.
unfriendlyadjective	Not kind or welcoming; showing dislike or hostility toward others.	The new neighbor seemed unfriendly and never said hello to anyone.
unhealthyadjective	Harmful to physical or mental health, or not in a state of good health.	Eating fast food every single day can become an unhealthy habit.
unhelpfuladjective	Not providing useful assistance, advice, or support when it is needed.	The customer service representative was unhelpful and refused to answer basic questions.
uninterestedadjective	Not curious about or concerned with something; lacking interest.	He seemed uninterested in the museum and kept checking his phone.
unlikelyadjective	Not likely to happen, be true, or be the case.	It is unlikely that the flight will arrive on time given the heavy storm.
unlockverb	To open something using a key or code, or to make something accessible that was previously restricted.	She quickly unlocked the front door and stepped inside out of the rain.
unluckyadjective	Having or bringing bad luck; not fortunate in outcome or timing.	He felt unlucky after missing the bus by only a few seconds.
unnaturaladjective	Different from what is normal, expected, or found in nature; forced, artificial, or strange.	There was something unnatural about the stillness of the forest that morning.
unnecessaryadjective	Not needed or required; more than is essential for a particular purpose.	He removed several unnecessary steps to make the process faster.
unpackverb	To remove the contents from a suitcase, box, or bag after arriving somewhere.	We spent the whole afternoon unpacking boxes after moving into the new apartment.
unpleasantadjective	Causing discomfort, dislike, or displeasure; not pleasant to experience, see, or be around.	The smell coming from the kitchen bin was too unpleasant to ignore any longer.
unpopularadjective	Not liked, favored, or supported by most people in a group.	The mayor's new tax increase proved deeply unpopular with local voters.
unpredictableadjective	Not able to be known or foreseen in advance; likely to change without warning.	Mountain weather can be unpredictable, changing from sunshine to storm within an hour.
unrealadjective	Not seeming real; strange, dreamlike, or hard to believe.	Standing at the edge of the canyon, the view felt almost unreal.
unreliableadjective	Not able to be trusted to behave, perform, or produce results consistently as expected.	The old car was too unreliable to drive on a long road trip.
unsafeadjective	Likely to cause harm or danger; not safe.	The bridge was declared unsafe after inspectors found cracks in its supports.
unwillingadjective	Not wanting to do something; reluctant or opposed to an action.	He was unwilling to apologize even after admitting his mistake.

What does the prefix un- mean?

Un- is one of the most common prefixes in English, and it typically means not or the reverse of. Adding it to happy gives unhappy, meaning not happy, and adding it to lock gives unlock, meaning to reverse a locked state. Most un- words pair with a recognizable base word, which makes this prefix one of the easiest patterns to spot and use when building vocabulary.

Frequently asked questions

What does the prefix un- mean?

It usually means not or the opposite of, as in unhappy or unfair.

Can un- be added to any word?

No, it only works with certain base words; some words that start with un-, like uncle or under, are not built from this negating prefix at all.