The activities of the fifth column, secretly undermining another organization.

(Christianity, Quakerism) Thursday (the fifth day of the Judeo-Christian seven day week)

plural of fifth grader

(US, education) A pupil who is in fifth grade.

Synonym of diminished fifth

(neuroanatomy) Synonym of trigeminal nerve.

Any of various men who worked closely with the Beatles, including George Martin, Pete Best, Stuart Sutcliffe, and Billy Preston.

plural of fifth rate

plural of fifth-rate

(UK, military, nautical, historical) Of a Royal Navy warship in the Napoleonic Era: having 32–44 guns across one or two gun decks, a complement of 200–300, and weighing 700–1,450 tons burthen.