(Wikimedia jargon) On the English Wikipedia, a rule that states that an editor must not perform more than three reverts on a single page—whether involving the same or different material—within a 24-hour period.

(sports) A rule whereby, in case of an aggregate draw, the team with the most away goals wins.

(advertising) A rule prohibiting the use of actors dressed as medical professionals to give a misleading impression of the medical benefits of a product being advertised.

plural of exception that proves the rule

A rule, applied to some controversial debates and discussion panels, stating that anybody who attends is free to use information from the discussion, but cannot reveal who made any comment.

(US, often used attributively) One of two classes of cities in the U.S. state of Kentucky, with cities under this class practicing home rule.

(chemistry) Synonym of Lipinski's rule of five

(chemistry) A rule of thumb stating that a chemical compound is likely to be an orally active drug in humans unless it violates more than one of these criteria: (i) no more than 5 hydrogen bond donors (the total number of nitrogen–hydrogen and oxygen–hydrogen bonds); (ii) no more than 10 hydrogen bond acceptors (all nitrogen or oxygen atoms); (iii) a molecular mass less than 500 daltons; (iv) an octanol-water partition coefficient (log P) that does not exceed 5.

(software engineering) A humorous aphorism stating that the first 90% of the code accounts for the first 90% of the development time, and the remaining 10% of the code accounts for the other 90% of the development time.

Synonym of Pareto principle