diffident, shy, timid, unsure(adj)

lacking self-confidence

"stood in the doorway diffident and abashed"; "problems that call for bold not timid responses"; "a very unsure young man"

uncertain, unsure, incertain(adj)

lacking or indicating lack of confidence or assurance

"uncertain of his convictions"; "unsure of himself and his future"; "moving with uncertain (or unsure) steps"; "an uncertain smile"; "touched the ornaments with uncertain fingers"

unsure(adjective)ənʃˈʊr

≠ sure

I'm unsure about whether to take the job.; unsure of his rights in the situation

unsure(Adjective)

uncertain of the facts

unsure(Adjective)

unstable or precarious