air pump

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A pump for compressing, removing, or forcing a flow of air.

from The Century Dictionary.

• noun An apparatus for the exhaustion, compression, or transmission of air.

from the GNU version of the Collaborative International Dictionary of English.

• (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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A pump that moves air either into, or out of, something.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a pump that moves air in or out of something