英语词源字典 - 在线词源网站

back up (v.)[back up 词源字典]: 1767, "stand behind and support," from back (v.) + up. The noun meaning "a standby, a reserve" is recorded from 1952 (often written as one word, backup); specific reference to computing is from 1965.[back up etymology, back up origin, 英语词源]
stand-by (n.): also standby, 1796, "that which stands by one," originally nautical, of a vessel kept nearby for emergencies, from verbal phrase stand by "await, support, remain beside" (mid-13c.); see stand (v.) + by. Meaning "state of being ready for duty" is from 1946. In civil aviation, as an adjective meaning "without a booked ticket," from 1961. As an order to hold one's self in readiness, it is recorded from 1660s.