1.Definition: ambiguous (especially in the negative)
"She spoke in no uncertain terms"
2.Definition: lacking or indicating lack of confidence or assurance
"Uncertain of his convictions", "Moving with uncertain (or unsure) steps", "An uncertain smile", "Touched the ornaments with uncertain fingers"
3.Definition: not certain to occur; not inevitable
"Everything is uncertain about the army", "The issue is uncertain"
4.Definition: not consistent or dependable
"An uncertain recollection of events", "A gun with a rather uncertain trigger"
5.Definition: not established beyond doubt; still undecided or unknown
"An uncertain future", "A manuscript of uncertain origin", "Plans are still uncertain", "Changes of great if uncertain consequences", "Without further evidence his story must remain uncertain"
6.Definition: not established or confirmed