Origin and history of windbag

"small sack," c. 1200, bagge, probably from Old Norse baggi "pack, bundle," or a similar Scandinavian source. OED rejects connection to other Germanic words for "bellows, belly" as without evidence and finds a Celtic origin untenable. In some senses perhaps from Old French bague, which is also from Germanic.

As disparaging slang for "woman" it dates from 1924 in modern use (but various specialized senses of this are much older, and compare baggage). The meaning "person's area of interest or expertise" is by 1964, from African-American vernacular, from jazz sense of "category," probably via notion of putting something in a bag. The meaning "fold of loose skin under the eye" is by 1867. Related: bags.

Many figurative senses, such as the verb meaning "to kill game" (1814) and its colloquial extension to "catch, seize, steal" (1818) are from the notion of the game bag (late 15c.) into which the product of the hunt was placed. This also probably explains modern slang in the bag "assured, certain" (1922, American English). To be left holding the bag (and presumably nothing else), "cheated, swindled" is attested by 1793.

To let the cat out of the bag "reveal the secret" is from 1760. The source is probably the French expression Acheter chat en poche "buy a cat in a bag," which is attested in 18c. French and explained in Bailey's "Universal Etymological English Dictionary" (1736), under the entry for To buy a pig in a poke as "to buy a Thing without looking at it, or enquiring into the Value of it." (Similar expressions are found in Italian and German; and in English, Wycliffe (late 14c.) has To bye a catte in þo sakke is bot litel charge). Thus to let the cat out of the bag would be to inadvertently reveal the hidden truth of a matter one is attempting to pass off as something better or different, which is in line with the earliest uses in English.

Sir Joseph letteth the cat out of the bag, and sheweth principles inimical to the cause of true philosophy, by wishing to make great men Fellows, instead of wise men. ["Peter Pindar," "Peter's Prophecy," 1788]

"air naturally in motion; a perceptible current of air from a particular direction;" Old English wind, from Proto-Germanic *winda-, from PIE *wē-nt-o‑ "blowing," suffixed (participial) form of root *we- "to blow."

Normal pronunciation evolution made this word rhyme with kind and rind (Donne rhymes it with mind and Thomas Moore with behind), but it shifted to a short vowel 18c., probably from influence of windy, where the short vowel is natural.

Symbolic of emptiness and vanity since c. 1200; from Middle English also of swiftness, transience, changeability.

I have forgot much, Cynara! gone with the wind. [Ernest Dowson, 1896]

With suggestion of force, agency, influence also by c. 1200, from wind as the driving force of a vessel on water. As in winds of change, a phrase attested by 1905 but popularized in Harold Macmillan's 1960 South Africa speech. Other images are from winds as favorable or not for navigation. To take the wind out of (one's) sails in the figurative sense (by 1883) is an image from sailing, where a ship without wind can make no progress.

The meaning "breath in and out of the lungs" is attested from late Old English; especially "breath in speaking" (early 14c.); hence long-winded. It also meant "easy or regular breathing" (early 14c.), hence second wind in the figurative sense (by 1830), an image from the sport of hunting. The meaning "part of the abdomen where a blow causes temporary loss of breathing power" is by 1823 in pugilism slang (see wind (v.2)).

As "air contained in something" (as in windbag), from late Old English. By mid-14c. as "gas in the body," especially air in the digestive organs.

Winds "orchestral instruments that produce sound by streams of breath or air" is by 1876, from wind-instrument. Also compare windfall, windbreak, etc. An old word for a broad-brimmed hat was wind-cutter (1610s).

The figurative phrase which way the wind blows for "the current state of affairs" is suggested from mid-14c. (how þe wynd was went). To get wind of "receive information about" is by 1809, perhaps inspired by French avoir le vent de.

Wind-chill index, to measure the cooling factor of wind, is recorded from 1939. Wind energy is attested by 1976. Wind vane is from 1725. Wind-shear by 1951.

Germanic cognates include Old Saxon, Old Frisian, Middle Dutch, Dutch wind, Old Norse vindr, Old High German wind, German Wind, Gothic winds.