air-mattress (n.)

c. 1300, "invisible gases that surround the earth," from Old French air "atmosphere, breeze, weather" (12c.), from Latin aer "air, lower atmosphere, sky," from Greek aēr (genitive aeros) "mist, haze, clouds," later "atmosphere" (perhaps related to aenai "to blow, breathe"), which is of unknown origin. It is possibly from a PIE *awer- and thus related to aeirein "to raise" and arteria "windpipe, artery" (see aorta) on notion of "lifting, suspended, that which rises," but this has phonetic difficulties.

In Homer mostly "thick air, mist;" later "air" as one of the four elements. Words for "air" in Indo-European languages tend to be associated with wind, brightness, sky. In English, air replaced native lyft, luft (see loft (n.)). In old chemistry, air (with a qualifying adjective) was used of any gas.

To be in the air "in general awareness" is from 1875; up in the air "uncertain, doubtful" is from 1752. To build castles in the air "entertain visionary schemes that have no practical foundation" is from 1590s (in 17c. English had airmonger "one preoccupied with visionary projects"). Broadcasting sense (as in on the air, airplay) is by 1927. To give (someone) the air "dismiss" is from 1900. Air pollution is attested by 1870. Air guitar is by 1983. Air traffic controller is from 1956.

c. 1300, materas, "a bed consisting of a bag filled with soft and elastic material and usually tacked at short intervals to prevent the contents from slipping," from Old French materas (12c., Modern French matelas), from Italian materasso and directly from Medieval Latin matracium, borrowed in Sicily from medieval Arabic al-matrah "(the) large cushion or rug for lying on" (also source of Spanish almadraque "mattress," Provençal and Catalan-Latin almatrac), literally "the thing thrown down," from taraha "he threw (down)" with noun prefix ma-. In Middle English also materace, matrasse, etc.,; the modern spelling is attested by early 15c.