c. 1400, "not safe against attack," also "lacking certainty," from un- (1) "not" + sure (adj.).
a very unsure young man
unsure of himself and his future
moving with uncertain (or unsure) steps
unsuited
unsullied
unsung
unsupervised
unsupported
unsure
unsurmountable
unsurpassable
unsurpassed
unsuspected
unsuspecting
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