slang for "aviator," 1909, from bird (n.1) + man (n.).
Entries linking to birdman
bird n.1
"feathered, warm-blooded vertebrate animal of the Aves," Old English bird, a rare collateral form of bridd, originally meaning "young bird, nestling" (the usual Old English for "bird" being fugol, for which see fowl (n.)), which is of uncertain origin with no cognates in any other Germanic language. The suggestion that it is related by umlaut to brood and breed is rejected by OED as "quite inadmissible." The metathesis of -r- and -i- was complete 15c. (compare wright).
Despite its early attestation, bridd is not necessarily the oldest form of bird. It is usually assumed that -ir- from -ri- arose by metathesis, but here, too, the Middle English form may go back to an ancient period. [Liberman]
Up to c. 1400 it still often was used in the specific sense "the young of a bird, fledgling, nestling, chick," and of the young of other animals (bees, fish, snakes) and human children. Compare the usual Balto-Slavic words for "bird" (Lithuanian paukštis, Old Church Slavonic pŭtica, Polish ptak, Russian ptica, etc.), said to be ultimately from the same root as Latin pullus "young of an animal."
The proper designation of the feathered creation is in E. fowl, which in course of time was specially applied to the gallinaceous tribe as the most important kind of bird for domestic use, and it was perhaps this appropriation of the word which led to the adoption of the name of the young animal as the general designation of the race. [Hensleigh Wedgwood, "A Dictionary of English Etymology," 1859]
The figurative sense of "secret source of information" is from 1540s. The colloquial meaning "man, fellow, person" is from 1799.
Bird-watching is attested from 1897. Bird's-eye view "the view as seen from above, as if by a bird in flight," is from 1762. Phrase for the birds in reference to anything undesirable is recorded from 1944, supposedly in allusion to birds eating from droppings of horses and cattle. The bird-spider (1800) of the American tropics is a large sort of tarantula that can capture and kill small birds.
A byrde yn honde ys better than three yn the wode. [c. 1530]
The form with bush is attested by 1630s.
man n.
"a featherless plantigrade biped mammal of the genus Homo" [Century Dictionary], Old English man, mann "human being, person (male or female); brave man, hero;" also "servant, vassal, adult male considered as under the control of another person," from Proto-Germanic *mann- (source also of Old Saxon, Swedish, Dutch, Old High German man, Old Frisian mon, German Mann, Old Norse maðr, Danish mand, Gothic manna "man"), from PIE root *man- (1) "man." For the plural, see men.
Sometimes connected to root *men- (1) "to think," which would make the ground sense of man "one who has intelligence," but not all linguists accept this. Liberman, for instance, writes, "Most probably man 'human being' is a secularized divine name" from Mannus [Tacitus, "Germania," chap. 2], "believed to be the progenitor of the human race."
Specific sense of "adult male of the human race" (distinguished from a woman or boy) is by late Old English (c. 1000); Old English used wer and wif to distinguish the sexes, but wer began to disappear late 13c. and was replaced by man. Universal sense of the word remains in mankind and manslaughter. Similarly, Latin had homo "human being" and vir "adult male human being," but they merged in Vulgar Latin, with homo extended to both senses. A like evolution took place in Slavic languages, and in some of them the word has narrowed to mean "husband." PIE had two other "man" roots: *uiHro "freeman" (source of Sanskrit vira-, Lithuanian vyras, Latin vir, Old Irish fer, Gothic wair; see *wi-ro-) and *hner "man," a title more of honor than *uiHro (source of Sanskrit nar-, Armenian ayr, Welsh ner, Greek anēr; see *ner- (2)).
Man also was in Old English as an indefinite pronoun, "one, people, they." It was used generically for "the human race, mankind" by c. 1200. As a word of familiar address, originally often implying impatience, c.1400; hence probably its use as an interjection of surprise or emphasis, since Middle English but especially popular from early 20c.
As "a woman's lover," by mid-14c. As "adult male possessing manly qualities in an eminent degree," from 14c. Man's man, one whose qualities are appreciated by other men, is by 1873. Colloquial use of the Man for "the boss" is by 1918. To be man or mouse "be brave or be timid" is from 1540s. Meaning "piece with which a game (especially chess) is played" is from c. 1400.
Man-about-town "man of the leisure who frequents clubs, theaters, and other social resorts" is from 1734. Man of the world is from mid-14c. as "secular man, layman;" by early 15c. as "man experienced in the ways of the world, one able to take things in stride." To do something as one man "unanimously" is from late 14c.
So I am as he that seythe, 'Come hyddr John, my man.' [1473]
MANTRAP, a woman's commodity. [Grose, "Dictionary of the Vulgar Tongue," London, 1785]
At the kinges court, my brother, Ech man for himself. [Chaucer, "Knight's Tale," c. 1386]