Etymology
Advertisement
air-freshener (n.)
1945, from air (n.1) + agent noun from freshen.
Related entries & more 
Advertisement
mid-air (n.)

also midair, "the part of the air between the clouds and the air near the ground," from mid (adj.) + air (n.1).

Related entries & more 
air-shaft (n.)
long narrow passage for admitting air, 1690s, from air (n.1) + shaft (n.2).
Related entries & more 
air-lock (n.)

by 1851, "air-tight chamber in which operations are carried on under water," to regulate pressure for the safety of workers, from air (n.1) + lock (n.1) in the canal sense.

Related entries & more 
air-gun (n.)
1753, "gun in which condensed air propels the ball or bullet," 1753, from air (n.1) + gun (n.).
Related entries & more 
Advertisement
air-port (n.2)
"small opening in the side of a ship to admit air and light," 1788, from air (n.1) + port (n.2).
Related entries & more 
air-brake (n.)
brake that works by compressed air power, 1872, from air (n.1) + brake (n.1). Related: Air-brakes.
Related entries & more 
air-bag (n.)

"sealed bag filled with air," 1836, from air (n.1) + bag (n.). In early use a means of raising sunken ships, etc.; as an automobile safety feature by 1970.

Related entries & more 
air mail (n.)

also air-mail, airmail, 1913, from air (n.1) meaning "by aircraft" + mail (n.1). As a verb by 1919. Related: Air-mailed.

Related entries & more 
air-space (n.)

also airspace, by 1821 in reference to stove and furnace construction, from air (n.1) + space (n.). From 1852 in reference to the cubic contents of a room (with reference to the persons in it) in sanitary regulations for boarding rooms, hospitals, etc. In firearms, "a vacant space between the powder charge and the projectile" (1847). By 1910 as "portion of the atmosphere controlled by a country above its territory."

Related entries & more 

Page 2