The Collaborative International Dictionary of English v.0.48:

Thoth \Thoth\, n.
   1. (Myth.) The god of eloquence and letters among the ancient
      Egyptians, and supposed to be the inventor of writing and
      philosophy. He corresponded to the Mercury of the Romans,
      and was usually represented as a human figure with the
      head of an ibis or a lamb.
      [1913 Webster]

   2. (Zool.) The Egyptian sacred baboon.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Thoth
    n 1: Egyptian Moon deity with the head of an ibis; god of wisdom
         and learning and the arts; scribe of the gods