The Collaborative International Dictionary of English v.0.48:

Buggery \Bug"ger*y\, n. [OF. bougrerie, bogrerie, heresy. See
   Bugger.]
   Unnatural sexual intercourse; sodomy.
   [1913 Webster]

WordNet (r) 3.0 (2006):

buggery
    n 1: intercourse via the anus, committed by a man with a man or
         woman [syn: sodomy, buggery, anal sex, anal
         intercourse]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

BUGGERY, crim. law. The detestable crime of having commerce contrary to the
order of nature, by mankind with mankind, or with brute beasts, or by
womankind with brute beasts. 3 Inst. 58; 12 Co. 36; Dane's Ab. Index, h. t.;
Merl. Repert. mot Bestialie. This is a highly penal offence.