Source : Webster's Revised Unabridged Dictionary (1913)

Unbecoming \Un`be*com"ing\, a. [Pref. un- not + becoming.]
   Not becoming; unsuitable; unfit; indecorous; improper.

         My grief lets unbecoming speeches fall.  --Dryden.
   -- {Un`be*com"ing*ly}, adv. -- {Un`be*com"ing*ness}, n.

Source : WordNet®

unbecoming
     adj 1: considered inappropriate for or unattractive on a particular
            person; "an unbecoming style"
     2: not in keeping with accepted standards of what is right or
        proper in polite society; "was buried with indecent
        haste"; "indecorous behavior"; "language unbecoming to a
        lady"; "unseemly to use profanity"; "moved to curb their
        untoward ribaldry" [syn: {indecent}, {indecorous}, {uncomely},
         {unseemly}, {untoward}]