epitonium

ĕpĭtŏnĭum, ii, n., = ἐπιτόνιον (also written ĕpistŏmion = ἐπιστόμιον),

• a bung, stopple, the cock in a water-pipe, Varr. R. R. 3, 5, 16; Vitr. 9, 8, 11 al.; Sen. Ep. 86, 6; Dig. 19, 1, 17, § 8.