1580s, "unpetitioned, not approached with a request," from un- (1) "not" + past participle of solicit (v.). Meaning "not asked for, unsought" is from 1680s.
unsolicited junk mail
unskilled
unskillful
unsmiling
unsociable
unsold
unsolicited
unsolved
unsophisticated
unsorted
unsought
unsound