The Collaborative International Dictionary of English v.0.48:

autacoid \autacoid\ n.
   1. 1 any physiologically active internal secretion,
      especially one of uncertain classification.

   Syn: autocoid.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

autacoid
    n 1: any physiologically active internal secretion especially
         one of uncertain classification [syn: autacoid,
         autocoid]