Çy̆l'in-der, n.

n. [Fr. cylindre, Sp. & It. cilindro, Lat. cylindrus, Gr. κύλινδρος, from κυλίνδειν, κυλίειν, to roll.] (Geom.) A solid body which may be generated by the rotation of a parallelogram round one of its sides; or a body of roller like form, of which the longitudinal section is oblong, and the cross section is circular.

Cylinder of a gun, the bore of the barrel. — Cylinder of a steam-engine, a large cylindrical tube of metal in which the piston moves by the alternate admission and escape of steam.