Definition of "cylinder" []

• Mathematics The surface generated by a straight line intersecting and moving along a closed plane curve, the directrix, while remaining parallel to a fixed straight line that is not on or parallel to the plane of the directrix. (noun)
• Mathematics The portion of such a surface bounded by two parallel planes and the regions of the planes bounded by the surface. (noun)
• Mathematics A solid bounded by two parallel planes and such a surface, especially such a surface having a circle as its directrix. (noun)
• A cylindrical container or object. (noun)
• Engineering The chamber in which a piston of a reciprocating engine moves. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "We play it constantly … instead of marbles they are the little green alien men and the cylinder is a spaceship."
• "It consists of a small wooden cylinder, about three quarters of an inch in diameter, and 3 in. long; at one end of the cylinder is a cavity which holds the combustible, which is confined only by pasteboard or membrane, so that, when ignited, it will blow straight into the heart of the principal charge; the two wires of the electric circuit, entering at the other end of the cylinder, terminate upon the little wooden disc which forms the bottom of this cavity, so that the end of one wire is about a quarter of an inch from the other; the electric circuit is completed by drawing a dash with a blacklead-pencil across the tiny space of the wooden surface connecting the two ends of wire; and the fusee is then charged."
• "Our 20th century based mindset will seem to be so quaint in 90 years, just as the thought of recording sound onto a wax cylinder is so primitive to us."