mid-15c., "unlucky," from un- (1) "not" + fortunate (adj.). Infortunate in same sense is older. In late 18c.-early 19c., unfortunate woman was a polite way to say "prostitute." The noun meaning "one who is not fortunate" is recorded from 1630s.
an unfortunate turn of events
an unfortunate night for all concerned
unfortunate investments
an unfortunate decision
an unfortunate speech
an unfortunate choice of words
unforgivable
unforgiven
unforgiving
unforgotten
unformed
unfortunate
unfortunately
unfortune
unfounded
unfree
unfrequented