uncertain

adjective

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.

adjective

1. not able to be accurately known or predictedthe issue is uncertain
2. (when postpositive, often foll by of) not sure or confident (about)a man of uncertain opinion
3. not precisely determined, established, or decideduncertain plans
4. not to be depended upon; unreliablean uncertain vote
5. liable to variation; changeablethe weather is uncertain
6. in no uncertain terms
   1. unambiguously
   2. forcefully

adj.c.1300, “of indeterminate time or occurrence,” from un- (1) “not” + certain (adj.). Meaning “not fully confident” is recorded from late 14c. (implied in uncertainty). Related: Uncertainly. see in no uncertain terms.