testosterone

from WordNet (r) 3.0 (2006)

testosterone
    n 1: a potent androgenic hormone produced chiefly by the testes;
         responsible for the development of male secondary sex
         characteristics

from The Collaborative International Dictionary of English v.0.48

Testosterone \Tes*tos"ter*one\ (t[e^]s*t[o^]s"t[~e]r*[=o]n), n.
   [testes + o + sterone a steroid ketone.]
   a steroid hormone ({C19H28O2}) produced mostly in the testes,
   which is responsible for producing the secondary sexual
   characteristics of males.
   [PJC]