Pronunciation: (brē'&thslash;ur),[key] —n. 1. a pause, as for breath.
2. vigorous exercise that causes heavy breathing.
3. a person who breathes.
4. a vent in a container or covering, as in a casing for machinery or in a storage tank, to equalize interior and exterior pressure, permit entry of air, escape of fumes, or the like.
5. a device for providing air from the atmosphere to submerged or otherwise sealed-off persons, internal-combustion engines, etc.: the snorkel breather of a submarine.