The Collaborative International Dictionary of English v.0.48:

Hamadryas \Ha*ma"dry*as\ (h[.a]*m[=a]"dr[i^]*[a^]s), n. [L., a
   hamadryad. See Hamadryad.] (Zool.)
   The sacred baboon of Egypt (Cynocephalus Hamadryas).
   [1913 Webster]