Source : Webster's Revised Unabridged Dictionary (1913)

Unacceptable \Un`ac*cept"a*ble\, a.
   Not acceptable; not pleasing; not welcome; unpleasant;
   disagreeable; displeasing; offensive. --
   {Un`ac*cept"a*ble*ness}, n. -- {Un`ac*cept"a*bly}, adv.

Source : WordNet®

unacceptable
     adj 1: not adequate to give satisfaction; "the coach told his
            players that defeat was unacceptable"
     2: not acceptable; not welcome; "a word unacceptable in polite
        society"; "an unacceptable violation of personal freedom"
        [ant: {acceptable}]
     3: used of persons or their behavior; "impossible behavior";
        "insufferable insolence" [syn: {impossible}, {insufferable},
         {unsufferable}]
     4: not conforming to standard usage; "the following use of
        `access' was judged unacceptable by a panel of linguists;
        `You can access your cash at any of 300 automatic
        tellers'" [syn: {unaccepted}]