c. 1300, "act of exhibiting to view," from show (v.). Sense of "appearance put on with intention to deceive" is recorded from 1520s. Meaning "display, spectacle" is first recorded 1560s; that of "ostentatious display" is from 1713 (showy is from 1712). Sense of "entertainment program on radio or TV" is first recorded 1932. Meaning "third place in a horse race" is from 1925, American English (see the verb).
Show of hands is attested from 1789; Phrase for show "for appearance's sake" is from c. 1700. Show business is attested from 1850; shortened form show biz used in "Billboard" from 1942. Actor's creed the show must go on is attested from 1890. Show-stopper is from 1926; show trial first recorded 1937.[show etymology, show origin, 英语词源]