stand·by / ˈstan(d)ˌbī/ • n. (pl. -bys) readiness for duty or immediate deployment: buses were placed on standby for the trip to Washington. ∎ the state of waiting to secure an unreserved place for a journey or performance, allocated on the basis of earliest availability: passengers were obliged to go on standby. ∎ a person waiting to secure such a place. ∎ a person or thing ready to be deployed immediately, esp. if needed as backup in an emergency: a generator was kept as a standby in case of power failure | [as adj.] a standby rescue vessel. ∎ an operational mode of an electrical appliance in which the power is switched on but the appliance is not actually functioning.