The Collaborative International Dictionary of English v.0.48:

Irate \I*rate"\, a. [L. iratus, fr. irasci to be angry. See
   Ire.]
   Angry; incensed; enraged. [Recent]
   [1913 Webster]

         The irate colonel . . . stood speechless. --Thackeray.
   [1913 Webster]

         Mr. Jaggers suddenly became most irate.  --Dickens.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "irate":
   angered, angry, browned-off, choleric, cross, incensed, indignant,
   ireful, livid, mad, pissed, pissed-off, riled up, sore, ticked off,
   waxy, worked up, wrathful, wrathy, wroth, wrought-up