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 a place on standby.
a person or thing ready to be deployed immediately, especially if needed as backup in an emergency:
"a generator was kept as a standby in case of power failure" ·
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"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.