Source : Webster's Revised Unabridged Dictionary (1913)

Irascible \I*ras"ci*ble\, a. [L. irascibilis, fr. irasci to be
   angry, ira anger: cf. F. irascible. See {Ire}.]
   Prone to anger; easily provoked or inflamed to anger;
   choleric; irritable; as, an irascible man; an irascible
   temper or mood. -- {I*ras"ci*ble*ness}, n. -- {I*ras"ci*bly},
   adv.

Source : WordNet®

irascible
     adj 1: quickly aroused to anger; "a hotheaded commander" [syn: {choleric},
             {hotheaded}, {hot-tempered}, {quick-tempered}, {short},
             {short-tempered}]
     2: characterized by anger; "a choleric outburst"; "an irascible
        response" [syn: {choleric}]