From Longman Dictionary of Contemporary Englishstandbystand‧by1, stand-by /ˈstændbaɪ/ noun (plural standbys) 1 → on standby2 [countable]READY something that is kept ready so that it can be used when needed Powdered milk is a good standby in an emergency.
Examples from the Corpus
standby• a cheap standby ticket• My itinerary was unambitious compared with those of some of my fellow standbys.• Here's how to create delicious last-minute meals entirely from standbys in the store cupboard.• Duck... l'orange is an old standby on traditional French menus.• Heavy selling out of the Middle East was an old standby.• Police have now appealed to Hanger to give himself up peacefully but armed police are on standby.• To receive a call you must put it on standby.• The station was built to provide standby power in emergencies.• Oatmeal was Mom's standby for breakfast.• Pates and terrines, a useful standby, provide an adequate meal when accompanied by good bread and a salad.standbystandby2 adjective [only before noun] a standby ticket is one that you can get only if places become available, for example if other people cannot use their ticketsExamples from the Corpus
standby• A hotel's conventional boiler for heat production alone usually achieves 70% and standby electricity generators, 50%.• The council said the standby proposals were part of a package of budget cuts.• Non-landing standby trips are offered at £1 per person on some afternoon Sea-Cat routes.From Longman Business Dictionarystandbystand‧by1 /ˈstændbaɪ/ (also stand-by) nounTRAVEL1[countable] someone or something that is ready to be used when neededThe government has asked potential donor countries for 75,000 tonnes of grain as a standby.2[uncountable] when you are ready to travel on a plane, but can only do so if there are seats left when it is ready to leaveThe flight is full, but we can put you on standby.standbystandby2 (also stand-by) adjective [only before a noun]1TRAVELa standby ticket is a cheap ticket for a plane journey that you buy just before the plane leaves —standby adverbMost of the carriers would allow people to fly standby.2ECONOMICS a standby arrangement or agreement allows a member state of the INTERNATIONAL MONETARY FUND to receive money if it has serious financial problemsAbout $45 million was available in instalments under a standby arrangement.The International Monetary Fund has approved a new £596 million standby loan for Pakistan. 