Buggery is a term for gay male sex, or more specifically anal intercourse, often considered synonymous with Sodomy.
The word comes from the French "Bougre" which in origin meant "Bulgarian", and by extension heretical (the connection being with the Bogomil religious movement in 10th Century Bulgaria). It was first commonly applied to the Cathar or Albigensian movement in south-eastern France, which had some similarities with the Bogomils, and was brutally suppressed by the Catholic Church in the 13th century "Albigensian Crusade".
Robert Mills describes the treatment in a French illustrated manuscript called Bible Moralisée of the Benjamites (from a story in the Book of Judges Chapter 19, parallel to the story of Sodom): it labels the Benjamites as "sodomites" and
- "compares them explicitly with 'Bulgars and Albigensians' who 'adore and believe in the devil'; the complementary image depicts ... a male-male couple kissing."
See also Buggery Act 1533.