ˌeks(h)əˈlāshən noun
( -s )
Etymology: Middle English exhalacioun, from Middle French & Latin; Middle French exalation, from Latin exhalation-, exhalatio, from exhalatus (past participle of exhalare to exhale) + -ion-, -io -ion
1. : an exhaling or sending forth (as in steam or vapor) : evaporation , expiration
noisy exhalations of a locomotive
specifically : the action of forcing air out of the lungs by means of a complex of essentially reflex actions that involve changes in the diaphragm and in muscles of the abdomen and thorax which cause contraction of the chest cavity and lungs resulting in production of relative positive pressure within the lung so that air flows out until the pressure is restored to equality with that of the atmosphere
2. : something that is exhaled or given off or that rises in the form of gas, fumes, or steam : effluvium , emanation
a foul exhalation from the marsh