D defs.my
Entry 2 senses Webster, 1913

Air pump

/ĕr pŭmp/ · Air· pump · IPA
01 A kind of pump for exhausting air from a vessel or closed space; also, a pump to condense air or force it into a closed space.
  1. 1.
    A kind of pump for exhausting air from a vessel or closed space; also, a pump to condense air or force it into a closed space.(Physics)
  2. 2.
    A pump used to exhaust from a condenser the condensed steam, the water used for condensing, and any commingled air.(Steam Engines)