STANDBY
standby
(adjective) ready for emergency use; “a standby generator”; “a standby crew”
standby
(noun) something that can be relied on when needed
understudy, standby
(noun) an actor able to replace a regular performer when required
Source: WordNet® 3.1
Etymology
Noun
standby (countable and uncountable, plural standbies)
A state of readiness without immediate involvement; remaining in preparation for (a sudden or unforeseen event or situation).
(electronics) sleep mode
(travel) Waiting at the airport in the hope of getting a seat on a flight that is already booked out.
Something that is standard, well-tested, or frequently used.
Synonyms
• at the ready
Verb
standby (third-person singular simple present standbys, present participle standbying, simple past and past participle standbyed)
(proscribed, operations) To wait briefly, as for additional communication by radio or telephone; alternative spelling of stand by
Source: Wiktionary
Stand"-by`, n.
Definition: One who, or that which, stands by one in need; something upon
which one relies for constant use or in an emergency.
Source: Webster’s Unabridged Dictionary 1913 Edition