Definition from Wiktionary, the free dictionary
See also stand by
Alternative forms 
The noun is stressed on stand; the verb has stress on each part.
standby (plural standbys)
- State of readiness without being immediately involved.
- The troops were on standby in case of an attack.
- (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.
- That recipe is an old standby, and she keeps the ingredients around in case of unexpected guests.
state of readiness without being immediately involved
- (proscribed neologism, operations) Wait briefly: alternative spelling of stand by.
- Standby while I check that for you.
- For usage examples of this term, see the citations page.