Definition of: uncertain

(un·sûr′tən) adjective
1. Not certain; that cannot be relied upon; variable; changeful; fitful; erring: an uncertain friend; uncertain weather; an uncertain shot.
2. That cannot be certainly predicted; being of doubtful issue.
3. Not having certain knowledge or assured conviction.
4. Not surely or exactly known: a lady of uncertain age.
5. Having no exact or precise significance: uncertain phraseology. See synonyms under EQUIVOCAL, PRECARIOUS, VAGUE.
—un·cer′tain·ly adverb