(Internet slang, fandom slang, informal) The proposition that there are pornographic depictions of anything and everything, especially as fan art on the Internet.

(Internet slang, fandom slang, informal) The proposition that it is possible to find genderswapped versions of every fictional character, especially as fan art on the internet.

(photography, film, visual arts) A normative rule that an image should be mentally or representationally divided in three horizontally and diagonally, and that the focus of the image should not be in the center of the resulting shape.

A doctrine in antitrust law which applies to contracts which "unreasonably" inhibit trade.

(law) A notion of what should "count" as law.

(logic) Any of a set of rules used to construct well-formed formulas of a formal language.

(logic, proof theory) A rule for combining (or modifying) well-formed formulas of a formal language in a truth-preserving manner (to yield new well-formed formulas).

(trigonometry) law of cosines

(trigonometry) law of sines

(chemistry) A rule in chemistry that states that the sum of the hydrogen valence and the maximum oxygen valence is equal to eight.