What is Buggery?

Legal Definition
The British English term buggery is very close in meaning to the term sodomy, often used interchangeably in law and popular speech. It may also be a specific common law offence encompassing both sodomy and bestiality.
-- Wikipedia
Legal Definition
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.
-- Bouviers Law Dictionary
Legal Definition
A carnal copulation against nature; and this is either by the confusion of species,—that is to say, a man or a woman with a brute beast,—or of sexes, as a man with a man or man unnaturally with a woman. 3 Inst 58; 12 Coke, 36. Ausman v. Veal, 10 Ind. 356, 71 Am. Dee, 331; Com. v. J., 21 Pa. Co. Ct. R. 626.
-- Black's Law Dictionary
Legal Definition
A term applied to both bestiality and sodomy. See 10 Ind. 355, 71 Am. Dec. 331.
-- Ballentine's Law Dictionary