"person of Mexican heritage in the U.S.," 1947, from Mexican Spanish dialectal pronunciation of Mexicano "Mexican," with loss of initial unaccented syllable [Barnhart]. Said to have been in use among Mexican-Americans from c. 1911. Probably influenced by Spanish chico "boy," which also is used as a nickname. The adjective in English is attested by 1967. Fem. form is Chicana.