pederasty

from WordNet (r) 3.0 (2006)

pederasty
    n 1: sexual relations between a man and a boy (usually anal
         intercourse with the boy as a passive partner) [syn:
         {pederasty}, {paederasty}]

from The Collaborative International Dictionary of English v.0.48

Pederasty \Ped"er*as`ty\, n. [Gr. paiderasti`a: cf. F.
   p['e]d['e]rastie.]
   Sexual activity between two males; sodomy; the "crime against
   nature"; -- used especially when one partner is a boy.

   Note: The term "crime against nature" to refer to homosexual
         activity is now (2002) seldom used except by religious
         conservatives. It was in the 1913 Webster, and is left
         here for historical purposes.
         [1913 Webster + PJC]