a. [ Gr. &unr_; not blown through. ] (Med.) Devoid of air; free from air; as, an apneumatic lung; also, effected by or with exclusion of air; as, an apneumatic operation. [ Webster 1913 Suppl. ]

a. [ Auto- + pneumatic. ] Acting or moving automatically by means of compressed air. [ Webster 1913 Suppl. ]

a. [ Gastro- + pneumatic. ] (Anat.) Pertaining to the alimentary canal and air passages, and to the cavities connected with them; as, the gastropneumatic mucuos membranes. [ 1913 Webster ]

a. [ Hydro-, 1 + pneumatic: cf. F. hydropneumatique. ] Pertaining to, or depending upon, both liquid and gaseous substances; as, hydropneumatic apparatus for collecting gases over water or other liquids. [ 1913 Webster ]

. (Ordnance) A disappearing gun carriage in which the recoil is checked by cylinders containing liquid and air, the air when compressed furnishing the power for restoring the gun to the firing position. It is used with some English and European heavy guns. [ Webster 1913 Suppl. ]

n. A vehicle, as a bicycle, the wheels of which are fitted with pneumatic tires. [ archaic ] [ Webster 1913 Suppl. ]

{ } 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 ]

n. (Biol.) The state of being pneumatic, or of having a cavity or cavities filled with air; as, the pneumaticity of the bones of birds. [ 1913 Webster ]

n. [ Cf. F. pneumatique. ] [ 1913 Webster ]

1. That branch of science which treats of the mechanical properties of air and other elastic fluids, as of their weight, pressure, elasticity, etc. See Mechanics. [ 1913 Webster ]

2. (Philos. & Theol.) The scientific study or knowledge of spiritual beings and their relations to God, angels, and men. [ 1913 Webster ]