The Collaborative International Dictionary of English v.0.48:

Mick \Mick\, Mickey \Mickey\n.
   a person of Irish descent; -- an ethnic slur, offensive and
   disparaging.

   Syn: Paddy.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

Mick
    n 1: (ethnic slur) offensive term for a person of Irish descent
         [syn: Paddy, Mick, Mickey]

Moby Thesaurus II by Grady Ward, 1.0:

18 Moby Thesaurus words for "Mick":
   Aussie, Boche, Canuck, Chink, Guinea, Hunk, Hunkie, Jerry, Kraut,
   Krauthead, Mickey, Paddy, dago, frog, greaseball, greaser, limey,
   wetback