Yours, Etc.: Origins and Uses of 8 Sign-Offs
c.1200, "the young of a goat," from a Scandinavian source (cf. Old Norse kið "young goat"), from Proto-Germanic *kiðjom (cf. Old High German kizzi, German kitze, Danish and Swedish kid). Extended meaning of "child" first recorded as slang 1590s, established in informal usage by 1840s. Applied to skillful young thieves and pugilists since at least 1812. Kid stuff "something easy" is from 1913 (The phrase was in use about that time in reference to vaudeville acts or advertisements featuring children, and to children-oriented features in newspapers). Kid glove "a glove made of kidskin leather" is from 1680s; sense of "characterized by wearing kid gloves," therefore "dainty, delicate" is from 1856.
"tease playfully," 1839, earlier, in thieves' cant, "to coax, wheedle, hoax" (1811), probably from kid (n.), via notion of "treat as a child, make a kid of." Related: Kidded; kidding.
: his kid sister/ my kid cousinnoun
[fr kid, ''an infant goat''; bantering and fooling senses perhaps fr an alteration of dialect cod, ''hoax, fool'']
the young of the goat. It was much used for food (Gen. 27:9; 38:17; Judg. 6:19; 14:6). The Mosaic law forbade to dress a kid in the milk of its dam, a law which is thrice repeated (Ex. 23:19; 34:26; Deut. 14:21). Among the various reasons assigned for this law, that appears to be the most satisfactory which regards it as "a protest against cruelty and outraging the order of nature." A kid cooked in its mother's milk is "a gross, unwholesome dish, and calculated to kindle animal and ferocious passions, and on this account Moses may have forbidden it. Besides, it is even yet associated with immoderate feasting; and originally, I suspect," says Dr. Thomson (Land and the Book), "was connected with idolatrous sacrifices."