an enclosure, usually of sheet metal, that conducts heated or conditioned air.
Nerve and air duct, therefore, are the essentials; the rest is so much material in reserve for the process of the metamorphosis.
The Life of the Fly J. Henri Fabre
Thus the efficiency of fireplaces may be materially increased, the degree depending upon the character of the air duct installed.
Farmers’ Bulletin 1230 – Chimneys & Fireplaces A. M. Daniels
- Air embolism
noun the presence in the tissues and blood of a gas, such as air or nitrogen bubbles, caused by an injection of air or, in the case of nitrogen, by an abrupt and substantial reduction in the ambient pressure See decompression sickness Historical Examples Danger from air embolism is exceedingly doubtful, unless great quantities were […]
- Air engine
noun an engine that uses the expansion of heated air to drive a piston a small engine that uses compressed air to drive a piston Historical Examples The air engine would in many respects possess advantages over the steam engine, if it could be worked economically. Great Facts Frederick C. Bakewell
- Air equivalent
a measure of the effectiveness of a material in absorbing nuclear radiation, expressed as the thickness of an air layer (at 0° C and 1 atmosphere) causing the same absorption.
- Air express
an express service for shipping small packages of goods by air: includes ground pickup at origin and delivery at destination. the goods shipped by this service. to send or transport by air express: Your package will be air-expressed and should reach its destination tomorrow. pertaining to, using, or sent by air express: Your air-express package […]