The Collaborative International Dictionary of English v.0.48:

Tattoo \Tat*too"\, v. t. [imp. & p. p. Tattooed; p. pr. & vb.
   n. Tattooing.] [Of Polynesian origin; cf. New Zealand ta to
   tattoo, tatu puncturation (in Otaheite).]
   To color, as the flesh, by pricking in coloring matter, so as
   to form marks or figures which can not be washed out.
   [1913 Webster]