Siphúnculus, siphúnculi, pen. cor. m. g. Diminutiunm, Pli. iun. A cock in a conduite.
Lewis and Short: Latin dictionary
sīphuncŭlus, i, m.dim. [sipho], a little pipe from which water springs forth, Plin. Ep. 5, 6, 23; 5, 6, 36.—Also written without the aspirate, sīpuncŭlus, Fronto, Or. 1 med.