Sodomy (/ˈsɒdəmi/), also called buggery in British English, principally refers to either anal sex (but occasionally also oral sex) between people, or any sexual activity between a human and another animal (bestiality). It may also mean any non-procreative sexual activity (including manual sex). Originally the term sodomy, which is derived from the story of Sodom and Gomorrah in the Book of Genesis, was commonly restricted to homosexual anal sex. Sodomy laws in many countries criminalized the behavior. In the Western world, many of these laws have been overturned or are routinely not enforced. A person who practices sodomy is sometimes referred to as a sodomite, a pejorative term.

The term is derived from the Ecclesiastical Latin peccatum Sodomiticum, "sin of Sodom", which in turn comes from the Ancient Greek word Σόδομα (Sódoma). Genesis (chapters 18–20) tells how God destroyed the sinful cities of Sodom and Gomorrah. Two angels sent to the cities are invited by Lot to take refuge with his family for the night. The men of Sodom surround Lot's house and demand that he bring out the strangers so that they may "know" them (a euphemism for sexual intercourse). Lot protests that the messengers are his guests and offers the Sodomites his virgin daughters instead, but then they threaten to "do worse" with Lot than they would with his guests. Then the angels strike the Sodomites blind, "so that they wearied themselves to find the door". (Genesis 19:4–11, KJV)

In current usage the term is particularly used in law. Laws prohibiting sodomy were seen frequently in past Jewish, Christian, and Islamic civilizations, but the term has little modern usage outside Africa, Asia, and the United States.

These laws in the United States have been challenged and have sometimes been found unconstitutional or been replaced with different legislation.

The word sod, a noun or verb (to "sod off") used as an insult, is derived from sodomite. It is a general-purpose insult term for anyone the speaker dislikes without specific reference to their sexual behaviour. Sod is used as slang in the United Kingdom and the Commonwealth and is considered mildly offensive. (The word 'sod' also has a meaning of "(clump of) earth" with an unrelated etymology, in which sense it is rare but not offensive.)

Many cognates in other languages, such as French sodomie (verb sodomiser), Spanish sodomía (verb sodomizar), and Portuguese sodomia (verb sodomizar), are used exclusively for penetrative anal sex, at least since the early 19th century. In those languages, the term is also often current vernacular (not just legal, unlike in other cultures) and a formal way of referring to any practice of anal penetration; the word sex is commonly associated with consent and pleasure with regard to all involved parties and often avoids directly mentioning two common aspects of social taboo – human sexuality and the anus – without a shunning or archaic connotation to its use.

In modern German the word Sodomie has no connotation of anal or oral sex and specifically refers to bestiality. The same goes for the Polish sodomia. The Norwegian word sodomi carries both senses. In Danish, sodomi is rendered as "unnatural carnal knowledge with someone of the same sex or (now) with animals".

In Arabic and Persian, the word for sodomy, لواط (Arabic pronunciation: liwāṭ; Persian pronunciation lavât), is derived from the same source as in Western culture, with much the same connotations as English (referring to most sexual acts prohibited by the Qur'an). Its direct reference is to Lot (لوط Lūṭ in Arabic) and a more literal interpretation of the word is "the practice of Lot", but more accurately it means "the practice of Lot's people" (the Sodomites) rather than Lot himself.