The Collaborative International Dictionary of English v.0.48:

Sirrah \Sir"rah\, n. [Probably from Icel. s[imac]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." --Beau. & Fl.
   [1913 Webster]

         Go, sirrah, to my cell.                  --Shak.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sirrah
    n 1: formerly a contemptuous term of address to an inferior man
         or boy; often used in anger