{ } a. [ L. pneumaticus, Gr. &unr_;, fr. &unr_;, &unr_;, wind, air, &unr_; to blow, breathe; cf. OHG. fnehan: cf. F. pneumatique. Cf. Pneumonia. ] 1. Consisting of, or resembling, air; having the properties of an elastic fluid; gaseous; opposed to dense or solid. [ 1913 Webster ]

The pneumatical substance being, in some bodies, the native spirit of the body. Bacon. [ 1913 Webster ]

2. Of or pertaining to air, or to elastic fluids or their properties; pertaining to pneumatics; as, pneumatic experiments. “Pneumatical discoveries.” Stewart. [ 1913 Webster ]

3. Moved or worked by pressure or flow of air; as, a pneumatic instrument; a pneumatic engine. [ 1913 Webster ]

4. (Biol.) Fitted to contain air; Having cavities filled with air; as, pneumatic cells; pneumatic bones. [ 1913 Webster ]

5. Adapted for containing compressed air; inflated with air; as, a pneumatic cushion; a pneumatic tire, a tire formed of an annular tube of flexible fabric, as India rubber, suitable for being inflated with air. [ Webster 1913 Suppl. ]

Pneumatic action, or
Pneumatic lever (Mus.), a contrivance for overcoming the resistance of the keys and other movable parts in an organ, by causing compressed air from the wind chest to move them. --
Pneumatic dispatch, a system of tubes, leading to various points, through which letters, packages, etc., are sent, by the flow and pressure of air. --
Pneumatic elevator, a hoisting machine worked by compressed air. --
Pneumatic pile, a tubular pile or cylinder of large diameter sunk by atmospheric pressure. --
Pneumatic pump, an air-exhausting or forcing pump. --
Pneumatic railway. See Atmospheric railway, under Atmospheric. --
Pneumatic syringe, a stout tube closed at one end, and provided with a piston, for showing that the heat produced by compressing a gas will ignite substances. --
Pneumatic trough, a trough, generally made of wood or sheet metal, having a perforated shelf, and used, when filled with water or mercury, for collecting gases in chemical operations. --
Pneumatic tube. See Pneumatic dispatch, above. [ 1913 Webster ]