Pronunciation: (un-sûr'tn), [key]
1. not definitely ascertainable or fixed, as in time of occurrence, number, dimensions, or quality.
2. not confident, assured, or free from hesitancy: an uncertain smile.
3. not clearly or precisely determined; indefinite; unknown: a manuscript of uncertain origin.
4. vague; indistinct; not perfectly apprehended: an abstruse novel with uncertain themes.
5. subject to change; variable; capricious; unstable: a person of uncertain opinions.
6. ambiguous; unreliable; undependable: Her loyalties are uncertain.
7. dependent on chance or unpredictable factors; doubtful; of unforeseeable outcome or effect.
8. unsteady or flickering, as light; of changing intensity or quality.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.