Source : Webster's Revised Unabridged Dictionary (1913)

Sirrah \Sir"rah\, n. [Probably from Icel. s[=i]ra, fr. F. sire.
   See {Sir}.]
   A term of address implying inferiority and used in anger,
   contempt, reproach, or disrespectful familiarity, addressed
   to a man or boy, but sometimes to a woman. In sililoquies
   often preceded by ah. Not used in the plural. ``Ah, sirrah
   mistress.''

Source : WordNet®

sirrah
     n : formerly a contemptuous term of address to an inferior man
         or boy; often used in anger