1. Civ. Eng.an airtight chamber permitting passage to or from a space, as in a caisson, in which the air is kept under pressure.
2. the impedance in the functioning of a pump or a system of piping caused by the presence of an air bubble; vapor lock.
Pronunciation: (âr'lok"),[key] —v.t. to place in or confine to an air lock: to air-lock divers before they descend.