unclear

IPA/ˌʌnˈklɪə(r)/
KK[ənklˈɪr]IPA/ˌʌnˈklɪr/

unclear — adjective

  • unclearpositive
  • more unclearcomparative
  • most unclearsuperlative

1. Something that is unclear is difficult to understand, identify, or know for sure

1.adjectiveB1
Definition

Something that is unclear is difficult to understand, identify, or know for sure, often because the information is incomplete, vague, or not expressed in a straightforward way.

Example

The reason for the delay was unclear to the passengers waiting at the gate.

It remains unclear whether the museum will open on time after the flood damage.

impersonal: it remains unclear whether-clause

Common collocations
  • unclear reason
  • unclear instructions
  • unclear meaning
  • unclear whether/if/what
  • remains unclear
  • still unclear
Synonyms
  • vague

    suggests a lack of detail or precision rather than complete incomprehensibility

  • ambiguous

    stresses that something has more than one possible meaning

  • obscure

    suggests something is difficult to understand because it is little known or intentionally hidden

  • uncertain

    focuses on doubt about the truth or reliability of information

Antonyms
  • clear

    easy to understand, see, or know

  • obvious

    very easy to notice or understand

  • evident

    clearly seen or understood

Grammar Patterns

it + be + unclear + whether/if/what/why-clause

[noun] + be + unclear + to + [person]

unclear + [noun]

Usage Note

Frequently used with a dummy subject 'it' followed by a clause beginning with 'whether', 'if', or a question word ('what', 'why', 'where'). This sense can appear both before a noun (an unclear signal) and after a linking verb (the signal was unclear).

Common Mistakes

It is unclear that he will come.
It is unclear whether he will come.
After 'it is unclear', use 'whether' or 'if', not 'that' to introduce the question.
The instructions were unclear explained.
The instructions were unclear.' or 'The instructions were not explained clearly.
'Unclear' is an adjective; do not use it to modify a verb.

2. A person who is unclear on a subject cannot say for sure what is true or what to

2.adjectiveB1
Definition

A person who is unclear on a subject cannot say for sure what is true or what to think, usually because the available information is incomplete or confusing.

Example

Mizuki was unclear about the deadline and turned in her report a day late.

If you are unclear about anything on the form, please ask a staff member at the desk.

conditional instruction: if + be unclear about + noun

Common collocations
  • unclear about
  • unclear as to
  • unclear on
  • still unclear about
  • unclear about the details
  • unclear about the rules
Synonyms
  • unsure

    more common in everyday conversation; sounds less formal

  • uncertain

    can also describe the situation itself, unlike this sense of 'unclear'

  • doubtful

    suggests stronger skepticism about the truth or outcome

Antonyms
  • certain

    having no doubts; completely sure

  • sure

    confident about something; more informal than 'certain'

  • clear

    fully understanding something; having no confusion

Grammar Patterns

[person] + be + unclear + about + [noun/question]

[person] + be + unclear + as to + wh-clause

[person] + be + unclear + on + [topic]

Usage Note

Always used predicatively — this sense describes a person's state of uncertainty, not a quality of the thing itself. You cannot say 'an unclear person' to mean someone who is uncertain; the person is unclear about something. Common prepositions: about (most frequent), as to (more formal), on (slightly less common).

Common Mistakes

I am unclear of the answer.
I am unclear about the answer.
The correct preposition after 'unclear' (in this sense) is 'about', 'as to', or 'on', not 'of'.
He is an unclear student about the rules.
He is unclear about the rules.
In this sense, 'unclear' cannot be placed before a noun; it must follow a linking verb like 'be' or 'feel'.

Word family

Synonym discussion

Sense: adjective/1

All four words describe something that is hard to understand, but they highlight different aspects. 'Unclear' is the broadest and most neutral term — it simply means not easy to see or know, without implying why. 'Vague' suggests a lack of detail or precision: a vague promise gives no specifics, while an unclear promise might just be poorly worded. 'Ambiguous' means the message has more than one possible interpretation: 'I saw her duck' is ambiguous because it could mean a bird or a motion. 'Obscure' goes further, suggesting the information is hard to find or deliberately hidden, or that the topic is known only to a few specialists. For everyday use, 'unclear' is the safest choice; switch to 'vague' when describing something that should have more detail, and 'ambiguous' when multiple meanings are the issue.

unclear ↗vague ↗ambiguous ↗obscure ↗

Common collocations

Nouns

  • unclear reason
  • unclear instructions
  • unclear meaning
  • unclear policy
  • unclear details

Adverbs

  • still unclear
  • somewhat unclear
  • completely unclear
  • totally unclear
  • increasingly unclear

Phrases

  • remain unclear
  • leave something unclear
  • it is unclear whether/if

Prepositions

  • unclear to (sense 1)
  • unclear about (sense 2)
  • unclear as to (sense 2)
  • unclear on (sense 2)

Etymology

GermanicOld FrenchLatinEnglish

Formed in Middle English by adding the prefix un- (meaning 'not') to the adjective 'clear'. 'Clear' comes from Old French 'cler', which traces back to Latin 'clarus' meaning 'bright, shining, clear, famous'. The prefix un- is Germanic in origin, making 'unclear' a hybrid of Germanic and Latin roots — a common pattern in English.