unsure

unsure — adjective

1. feeling that you do not know something or cannot decide what to do because the f

1.adjectiveB1
Definition

feeling that you do not know something or cannot decide what to do because the facts are not clear enough

Example

Otis was unsure whether to accept the job offer in another city.

unsure + whether + to-infinitive

Many voters remain unsure which candidate to support in the upcoming election.

unsure + which + wh-word + to-infinitive

Common collocations
  • unsure whether + to-infinitive
  • unsure what/which/how + to-infinitive
  • unsure about + noun/gerund
  • unsure of + noun phrase
  • remain unsure
  • leave someone unsure
Synonyms
  • uncertain

    Nearly identical in meaning; uncertain can also apply to outcomes or facts (e.g. the outcome is uncertain), while unsure is more about a person's state of doubt.

  • doubtful

    Emphasizes skepticism about the truth or likelihood of something, whereas unsure focuses on personal lack of knowledge or confidence in a decision.

  • undecided

    Specifically about a choice that has not yet been made; undecided implies an active decision is pending, while unsure may refer to the feeling itself.

  • hesitant

    Describes reluctance to act, often because of fear or doubt; hesitant suggests a behavioral pause, whereas unsure is primarily a mental state.

Antonyms
  • certain

    The direct opposite: having no doubt about something.

  • sure

    Very close to certain; sure is slightly less formal and more common in everyday speech.

  • confident

    Implies a stronger, more active feeling of certainty than sure or certain.

Grammar Patterns

be + unsure + whether/what/which/how + to-infinitive

be + unsure + about + noun/gerund

be + unsure + of + noun phrase

Usage Note

Commonly followed by a wh-clause (whether, what, which, how) or about + noun phrase. The that-clause is less frequent but possible (e.g. 'I am unsure that this plan will work'). Unlike the adjective uncertain, unsure rarely takes a simple noun object without a preposition.

Common Mistakes

I'm unsure to go to the party.
I'm unsure whether to go to the party.
Unsure does not link directly to a to-infinitive; a wh-word such as whether or what is needed between them.
She was unsure if the package had arrived.
She was unsure whether the package had arrived.
Although if is common in speech, whether is preferred in formal writing after unsure when there is a clear choice.

2. not feeling sure about your own ability, skills, or value as a person

2.adjectiveB1
Definition

not feeling sure about your own ability, skills, or value as a person

Example

As a new teacher, Hamza felt unsure about leading his first class discussion.

unsure about + gerund phrase

After the criticism, Nora became unsure of her ability to write well.

unsure of + noun phrase referring to self

Common collocations
  • unsure of + reflexive pronoun
  • unsure about + noun/gerund (self-referring)
  • feel unsure
  • look unsure
  • appear unsure
  • painfully unsure
Synonyms
  • insecure

    Stronger and more emotional than unsure; insecure often suggests a lasting lack of self-worth rather than a temporary feeling of doubt.

  • self-doubting

    More specific to questioning one's own abilities; slightly more formal and less common in everyday speech.

  • diffident

    Formal term meaning shy or lacking confidence; diffident implies a personality trait, whereas unsure is often situational.

Antonyms
  • confident

    The direct opposite: feeling sure of one's own abilities and worth.

  • self-assured

    Describes a person who is quietly and steadily confident.

  • self-confident

    Emphasizes belief in one's own skills and judgment.

Grammar Patterns

be + unsure + of + reflexive pronoun

feel/look/seem + unsure

be + unsure + about + noun/gerund

Usage Note

Subject is always a person or a group of people. Frequently constructed with a reflexive pronoun (unsure of myself/himself/themselves). Common with linking verbs such as feel, look, seem, and appear, which describe the person's outward or inner state. This sense does not take a that-clause or a wh-clause about facts.

Common Mistakes

He is unsure of him.
He is unsure of himself.
Use the reflexive pronoun (myself, yourself, himself, herself, ourselves, themselves), not the object pronoun, when expressing self-doubt.
I am unsure of my job.' (trying to mean 'I lack confidence at work')
I am unsure of myself at work.
Without myself/themselves, unsure of + noun can be read as the NOT CERTAIN sense about external facts.

Word family

Synonym discussion

Sense: adjective/1

All four words describe a lack of certainty, but they differ in focus and use. Uncertain is the closest synonym to unsure and is broadly interchangeable, though uncertain can also describe external facts that are not known (e.g., 'the cause is uncertain'), whereas unsure is more about a person's internal state. Doubtful adds skepticism about the truth or likelihood of something ('I am doubtful that the plan will work') — it implies the speaker leans toward a negative conclusion. Undecided is narrower: it applies only when a choice has not yet been made and an active decision is still pending. Hesitant points to a behavioral pause or reluctance to act, often because of fear or doubt, rather than a purely mental state of not knowing ('she was hesitant to speak up'). In practice, someone can be unsure without being hesitant — they may simply lack information — and undecided without being doubtful — they may consider both options equally valid.

uncertain ↗doubtful ↗undecided ↗hesitant

Common collocations

Adverbs

Phrases

  • unsure as to
  • unsure whether

Prepositions

Etymology

LatinFrenchEnglish

Formed in Middle English by adding the negative prefix un- to sure, which came into English from Old French seür, meaning 'safe, secure, reliable'. The French word traces back to Latin securus, meaning 'free from care' — from se- ('without') and cura ('care, worry'). The sense of 'free from doubt' developed in the 1400s, and the negative unsure appeared soon afterward to describe the absence of that certainty.