Source : Webster's Revised Unabridged Dictionary (1913)

Unpleasant \Un*pleas"ant\, a.
   Not pleasant; not amiable or agreeable; displeasing;
   offensive. -- {Un*pleas"ant*ly}, adv. -- {Un*pleas"ant*ness},
   n.

Source : WordNet®

unpleasant
     adj 1: not pleasant; "an unpleasant personality"; "unpleasant
            repercussions"; "unpleasant odors" [ant: {pleasant}]
     2: causing disapproval or protest; "a vulgar and objectionable
        person" [syn: {objectionable}, {obnoxious}]
     3: very unpleasant or annoying