Source : Webster's Revised Unabridged Dictionary (1913)

Chopfallen \Chop`fall`en\, a.
   Having the lower chop or jaw depressed; hence, crestfallen;
   dejected; dispirited; downcast. See {Chapfallen}.

Source : WordNet®

chopfallen
     adj : brought low in spirit; "left us fatigued and deflated
           spiritually" [syn: {chapfallen}, {crestfallen}, {deflated}]