Air lock

Air Air ([^a]r), n. [OE. air, eir, F. air, L. a["e]r, fr. Gr. 'ah`r, air, mist, for 'a[digamma]hr, fr. root 'a[digamma] to blow, breathe, probably akin to E. wind. In sense 10 the French has taking a meaning fr. It. aria atmosphere, air, fr. the same Latin word; and in senses 11, 12, 13 the French meaning is either fr. L. aria, or due to confusion with F. aire, in an older sense of origin, descent. Cf. {A["e]ry}, {Debonair}, {Malaria}, {Wind}.] 1. The fluid which we breathe, and which surrounds the earth; the atmosphere. It is invisible, inodorous, insipid, transparent, compressible, elastic, and ponderable. [1913 Webster]

Note: By the ancient philosophers, air was regarded as an element; but modern science has shown that it is essentially a mixture of oxygen and nitrogen, with a small amount of carbon dioxide, the average proportions being, by volume: oxygen, 20.96 per cent.; nitrogen, 79.00 per cent.; carbon dioxide, 0.04 per cent. These proportions are subject to a very slight variability. Air also always contains some vapor of water. [1913 Webster]

2. Symbolically: Something unsubstantial, light, or volatile. ``Charm ache with air.'' --Shak. [1913 Webster]

He was still all air and fire. [Air and fire being the finer and quicker elements as opposed to earth and water.] --Macaulay . [1913 Webster]

3. A particular state of the atmosphere, as respects heat, cold, moisture, etc., or as affecting the sensations; as, a smoky air, a damp air, the morning air, etc. [1913 Webster]

4. Any a["e]riform body; a gas; as, oxygen was formerly called vital air. [Obs.] [1913 Webster]

5. Air in motion; a light breeze; a gentle wind. [1913 Webster]

Let vernal airs through trembling osiers play. --Pope. [1913 Webster]

6. Odoriferous or contaminated air. [1913 Webster]

7. That which surrounds and influences. [1913 Webster]

The keen, the wholesome air of poverty. --Wordsworth. [1913 Webster]

8. Utterance abroad; publicity; vent. [1913 Webster]

You gave it air before me. --Dryden. [1913 Webster]

9. Intelligence; information. [Obs.] --Bacon. [1913 Webster]

10. (Mus.) (a) A musical idea, or motive, rhythmically developed in consecutive single tones, so as to form a symmetrical and balanced whole, which may be sung by a single voice to the stanzas of a hymn or song, or even to plain prose, or played upon an instrument; a melody; a tune; an aria. (b) In harmonized chorals, psalmody, part songs, etc., the part which bears the tune or melody -- in modern harmony usually the upper part -- is sometimes called the air. [1913 Webster]

11. The peculiar look, appearance, and bearing of a person; mien; demeanor; as, the air of a youth; a heavy air; a lofty air. ``His very air.'' --Shak. [1913 Webster]

12. Peculiar appearance; apparent character; semblance; manner; style. [1913 Webster]

It was communicated with the air of a secret. --Pope. [1913 Webster]

12. pl. An artificial or affected manner; show of pride or vanity; haughtiness; as, it is said of a person, he puts on airs. --Thackeray. [1913 Webster]

14. (Paint.) (a) The representation or reproduction of the effect of the atmospheric medium through which every object in nature is viewed. --New Am. Cyc. (b) Carriage; attitude; action; movement; as, the head of that portrait has a good air. --Fairholt. [1913 Webster]

15. (Man.) The artificial motion or carriage of a horse. [1913 Webster]

Note: Air is much used adjectively or as the first part of a compound term. In most cases it might be written indifferently, as a separate limiting word, or as the first element of the compound term, with or without the hyphen; as, air bladder, air-bladder, or airbladder; air cell, air-cell, or aircell; air-pump, or airpump. [1913 Webster]

{Air balloon}. See {Balloon}.

{Air bath}. (a) An apparatus for the application of air to the body. (b) An arrangement for drying substances in air of any desired temperature.

{Air castle}. See {Castle in the air}, under {Castle}.

{Air compressor}, a machine for compressing air to be used as a motive power.

{Air crossing}, a passage for air in a mine.

{Air cushion}, an air-tight cushion which can be inflated; also, a device for arresting motion without shock by confined air.

{Air fountain}, a contrivance for producing a jet of water by the force of compressed air.

{Air furnace}, a furnace which depends on a natural draft and not on blast.

{Air line}, a straight line; a bee line. Hence

{Air-line}, adj.; as, air-line road.

{Air lock} (Hydr. Engin.), an intermediate chamber between the outer air and the compressed-air chamber of a pneumatic caisson. --Knight.

{Air port} (Nav.), a scuttle or porthole in a ship to admit air.

{Air spring}, a spring in which the elasticity of air is utilized.

{Air thermometer}, a form of thermometer in which the contraction and expansion of air is made to measure changes of temperature.

{Air threads}, gossamer.

{Air trap}, a contrivance for shutting off foul air or gas from drains, sewers, etc.; a stench trap.

{Air trunk}, a pipe or shaft for conducting foul or heated air from a room.

{Air valve}, a valve to regulate the admission or egress of air; esp. a valve which opens inwardly in a steam boiler and allows air to enter.

{Air way}, a passage for a current of air; as the air way of an air pump; an air way in a mine.

{In the air}. (a) Prevalent without traceable origin or authority, as rumors. (b) Not in a fixed or stable position; unsettled. (c) (Mil.) Unsupported and liable to be turned or taken in flank; as, the army had its wing in the air.

{on the air}, currently transmitting; live; -- used of radio and television broadcasts, to indicate that the images and sounds being picked up by cameras and microphones are being broadcast at the present moment.

Note: In call-in programs where individuals outside a radio or television studio have telephoned into the station, when their voice is being directly broadcast, the host of the program commonly states ``You're on the air.'' as a warning that the conversation is not private.

{To take air}, to be divulged; to be made public.

{To take the air}, to go abroad; to walk or ride out. [1913 Webster]