noun
/ˈstændˌbaɪ/ , pl standbys /ˈstændˌbaɪz/
[count] :a person or thing that is available especially in emergencies
on standby
ready or available for immediate action or use
ready to travel if a ticket becomes available
adjective
always used before a noun
relating to or traveling by an airline service in which the passenger must wait for an available seat
US