A musical interval of the Western twelve-semitone system consisting of five semitones and spanning four degrees of the diatonic scale. It is enharmonically equivalent to an augmented third.

Having four feet.

Alternative form of fourche (“forked”)

A machine for making continuous rolls of paper.

plural of fourdrinier

Having four hands; quadrumanous. / Requiring four hands. / Requiring or involving four people.

a Fourier series consisting solely of sine functions

a Fourier series consisting solely of cosine functions

plural of fourgie

(slang) An act of group sex between four people; a foursome.