(neuroanatomy, anatomy) One of the four ventricles of the human brain

plural of fourth market

(finance) Direct trading between institutions, without the services of broker-dealers.

(advertising) The back cover of a publication.

plural of fourth cover

plural of foursome reel

(theater, film, television) A joke that intentionally draws attention to the illusion of separation between the audience and the fiction itself.

plural of fourth wall joke

Of or relating to the French mathematician and physicist Jean Baptiste Joseph Fourier. / Of or relating to Charles Fourier or his cooperative socialistic system called Fourierism.

plural of fourth rate