Source : Webster's Revised Unabridged Dictionary (1913)

Unexpected \Un`ex*pect"ed\, a.
   Not expected; coming without warning; sudden. --
   {Un`ex*pect"ed*ly}, adv. -- {Un`ex*pect"ed*ness}, n.

Source : WordNet®

unexpected
     adj 1: not expected or anticipated; "unexpected guests";
            "unexpected news" [ant: {expected}]
     2: not foreseen; "unsuspected difficulties arose"; "unsuspected
        turnings in the road"
     3: made necessary by an unexpected situation or emergency; "a
        forced landing" [syn: {forced}]
     4: causing surprise or amazement by not being expected; "the
        curtains opened to reveal a completely unexpected scene"
     5: not planned; "an unexpected pregnancy"
     6: happening or coming quickly and without warning; "a sudden
        unexpected development" [syn: {unforeseen}]