standby

American  

[stand-bahy] / ˈstændˌbaɪ /

Or stand-by

noun

plural

standbys

1. a staunch supporter or adherent; one who can be relied upon.

2. something upon which one can rely and therefore choose or use regularly.

3. something or someone held ready to serve as a substitute, especially a radio or television program used as a filler in case of cancellation of a regularly scheduled program.

4. a traveler who is waiting for last-minute accommodations to become available on a plane, train, or other transport as a result of a cancellation.

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adjective

1. kept readily available for use in an emergency, shortage, or the like.

   a standby player.

2. of or relating to last-minute accommodations, the transport that offers them, or a traveler who is waiting for them.

   a standby flight.

3. of or relating to a waiting period.

idioms

1. on standby, in a state of readiness to act, respond, or be used immediately when needed.

Etymology

Origin of standby

First recorded in 1790–1800; noun, adj. use of verb phrase stand by

Explanation

A standby is something (or someone) you can rely on in an emergency, like the bicycle you keep as a standby in case your old car won't start. In basketball, the players on the bench are the standbys for their teammates on the court; and in theater, an actor's understudy is her standby. When something is "on standby," it's ready to jump in or be used immediately. And when you fly on standby, you are ready to take an extra seat on a flight if one becomes available. Standby comes from nautical slang for "a vessel kept for emergencies," originally "that which stands by one."

Example Sentences

Ireland's armed forces have been put "on standby" to assist with clearing the blockades, defence minister Helen McEntee has said.

From Barron's • Apr. 10, 2026

While previous methods depended on high-powered lasers, this effect can be triggered with microwatts of power, far less than what a smartphone uses in standby mode.

From Science Daily • Mar. 27, 2026

Gomina in turn called the quick-reaction force, or QRF, an elite unit on standby for emergencies, to order a counterattack.

From The Wall Street Journal • Mar. 12, 2026

A team in Gibraltar remained on standby in case the connection failed, but it held throughout the procedure.

From BBC • Mar. 6, 2026

“Me getting home tomorrow morning? I’m supposed to be on standby here; the casting people told me I might be getting a call to come back in or something.”

From "Better Nate Than Ever" by Tim Federle