(UK politics, historical) A coalition committee that resolved party disputes during the Cameron–Clegg coalition.

(informal) An informal strategic forum between the United States, Japan, Australia, and India, focused on Asian security matters.

Involving four elements.

Having four shots of espresso.

A quad bike (from quadricycle) / Abbreviation of quadrillion BTU. (10¹⁵ BTU)

(informal) A quadrangle (quadrangular courtyard). / (informal) A quadruplet (infant). / (informal, computer graphics) A quadrilateral. / (informal) The quadriceps muscle.

(transitive)

to ride a quad bike

A serving of four shots of espresso. / (chess) A kind of round-robin tournament between four players, where each participant plays every other participant once.

(letterpress typography, transitive, intransitive) To fill spaces in a line of type with quads. Also quad out.