Longman Dictionary of Contemporary English
air pump
noun
EXAMPLES FROM CORPUS
▪ At the same time the air pump removes waste water and air from the separate condenser thus maintaining a vacuum in it.
▪ His other suggestions were in respect of a chemical pump and an air pump.
▪ His undergravel filter, therefore was best powered by an air pump rather than powerheads.
▪ The equipment need only be a sponge filter, air pump and heaterstat.
▪ When connected and adjusted, an air pump needs very little attention.
▪ Which you choose, an air pump or alternative means, is a matter of personal choice.
The Collaborative International Dictionary
Air pump
Air pump \Air" pump`\
(Physics) 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.
(Steam Engines) A pump used to exhaust from a condenser the condensed steam, the water used for condensing, and any commingled air.
Wiktionary
air pump
n. A pump that moves air either into, or out of, something.
WordNet
air pump
n. a pump that moves air in or out of something [syn: vacuum pump]
Wikipedia
Air pump
An air pump is a device for pushing air. Examples include a bicycle pump, pumps that are used to aerate an aquarium or a pond via an airstone; a gas compressor used to power a pneumatic tool, air horn or pipe organ; a bellows used to encourage a fire; a vacuum cleaner and a vacuum pump.