Cyl"in*der (s?l"?n-d?r), n. [F. cylindre, OF. cilindre, L. cylindrus, fr. Gr. ky`lindros, fr. kyli`ndein, kyli`ein, to roll. Cf. Calender the machine.]

1. (Geom.) (a) A solid body which may be generated by the rotation of a parallelogram round one its sides; or a body of rollerlike form, of which the longitudinal section is oblong, and the cross section is circular. (b) The space inclosed by any cylindrical surface. The space may be limited or unlimited in length.

2. Any hollow body of cylindrical form, as: (a) The chamber of a steam engine in which the piston is moved by the force of steam. (b) The barrel of an air or other pump. (c) (Print.) The revolving platen or bed which produces the impression or carries the type in a cylinder press. (d) The bore of a gun; the turning chambered breech of a revolver.

3. The revolving square prism carrying the cards in a Jacquard loom.

• (geometry) A surface created by projecting a closed two-dimensional curve along an axis perpendicular to the plane of the curve.
       When the two-dimensional curve is a circle, the cylinder is called a circular cylinder. In non-mathematical usage, circular is usually implied.
  
• (geometry) A solid figure bounded by a cylinder and two parallel planes intersecting the cylinder.
  
• Any object in the form of a circular cylinder.
  
• A cylindrical cavity or chamber in a mechanism, such as the counterpart to a piston found in a piston-driven engine.
  
• A container in the form of a cylinder with rounded ends for storing pressurized gas.
  
• An early form of phonograph recording, made on a wax cylinder.