Middle English chiken, from Old English cicen (plural cicenu) "young of the domestic hen, the young of any bird;" by early Middle English, "any chicken," regardless of age, from Proto-Germanic *kiukinam (source also of Middle Dutch kiekijen, Dutch kieken, Old Norse kjuklingr, Swedish kyckling, German Küken "chicken"), from root *keuk- (echoic of the bird's sound and possibly also the root of cock (n.1)) + diminutive suffixes. By regular sound changes it should have become Modern English *chichen; the reason it didn't is unknown.

 Generic words for "chicken" in Indo-European tend to be extended uses of "hen" words, as hens are more numerous than cocks among domestic fowl, but occasionally they are from words for the young, as in English and in Latin (pullus).

The meaning "one who is cowardly or timorous" is from 1610s; adjectival sense of "cowardly" is at least as old as 14c. (compare hen-herte "a chicken-hearted person," mid-15c.). As the name of a game of danger to test courage, it is recorded by 1953.

Chicken-feed "paltry sum of money" is by 1897, American English slang; literal use (it is made from the from lowest quality of grain) is by 1834. Chicken lobster "small lobster," is by 1947, American English, apparently from chicken in its sense of "young." To count (one's) chickens before they hatch "anticipate too confidently the obtaining or doing of something" is from 1570s. Chicken-fried steak (1937) is a U.S. Southern recipe that batters, breads, and fries a thin strip of steak in the way fried chicken typically is made.

"to back down or fail through cowardice," 1943, U.S. slang, from chicken (n.), almost always with out (adv.). Related: Chickened; chickening.

type of hawk that is believed to prey on domestic fowl, 1802, American English. Figuratively, from the secondary senses of both words, "public person who advocates war but declined significant opportunity to serve in uniform during wartime," at least 1988, American English. From chicken (n.) + hawk (n.).

c. 1730, from chicken (n.) + pox. Perhaps so called for its mildness compared to smallpox [Barnhart], or its generally appearing in children, or its resemblance to chick-peas.

"the young of the domestic hen," also of some other birds, mid-14c., probably originally a shortening of chicken (n.).

Extended 14c. to human offspring, "person of tender years" (often in alliterative pairing chick and child) and thence used as a term of endearment. As modern slang for "young woman" it is recorded by 1927 (in "Elmer Gantry"), supposedly from African-American vernacular. In British use in this sense by c. 1940; popularized by Beatniks late 1950s (chicken in this sense is by 1860). Sometimes c. 1600-1900 chicken was taken as a plural, chick as a singular (compare child/children) for the domestic fowl.

1947 (n.) "contemptible cowardly person;" 1948 (adj.); from chicken + shit (n.).

late 14c., originally as a chicken and rice dish similar to Turkish Tavukgöğsü, from Old French blancmengier (13c.), literally "white eating," from blanc "white" (also used in Old French of white foods, such as eggs, cream, also white meats such as veal and chicken; see blank (adj.)) + mangier "to eat" (see manger). The meat-free version first appears 16c. but was not the standard till 18c. Attempts were made to nativize the term (Chaucer has blankemangere); French pronunciation is evident in variant blomange, and "the present spelling is a half attempt at restoring the French" [OED].

"the young of a chicken or domestic fowl," mid-15c. (early 14c. in surnames), a contraction of Middle English pulte, itself a contraction of polete "young chicken" (see pullet).

"a short chirp, the cry of a mouse or young chick or other small bird," mid-15c., from peep (v.2); meaning "slightest sound or utterance" (usually in a negative context) is attested by 1903. Meaning "young chicken" is from 1680s. The marshmallow peeps confection are said to date from the 1950s.

mid-14c., past-participle adjective from fry (v.). Fried chicken attested by 1832.