standby

standby — noun

1. an object, piece of equipment, or other resource that is kept ready for use when

1.nounB2
Definition

an object, piece of equipment, or other resource that is kept ready for use whenever the usual item fails or cannot be obtained.

Example

The hospital keeps a standby generator in case the main power supply fails.

collocation: standby generator / standby equipment

When her laptop battery died, Anya took out the paper notebook she carries as a standby.

Common collocations
  • standby generator
  • standby equipment
  • standby vehicle
  • standby plan
  • quick standby
  • useful standby
Synonyms
  • backup

    more common in computing and general contexts; less formal

  • reserve

    suggests a stored supply rather than an immediate replacement

  • substitute

    focuses on the idea of replacement rather than readiness

Antonyms
  • primary

    the main item that is normally used

Grammar Patterns

standby + noun

a standby

Usage Note

Commonly combines with nouns that name equipment: standby generator, standby battery, standby vehicle. When used attributively (a standby plan), the hyphenated form stand-by is also possible in British English.

Common Mistakes

I always have a stand by in my car.
I always have a standby in my car.
As a noun, standby is written as one word, not two.

2. a state in which a person or group is ready and available to act or be used imme

2.nounB2
Definition

a state in which a person or group is ready and available to act or be used immediately if needed, especially during an emergency or a busy work period.

Example

The ambulance crew was on standby outside the concert hall in case of any medical emergencies.

phrase: on standby + for [event]

Christopher kept three extra nurses on standby during the night shift at the hospital.

Common collocations
  • on standby
  • keep someone on standby
  • put someone on standby
  • standby for
Synonyms
  • on alert

    suggests a higher level of urgency, often military

  • on call

    used especially for medical professionals available by phone

Antonyms

Grammar Patterns

on standby

put/keep someone on standby

Usage Note

Used almost exclusively in the fixed phrase on standby, which functions as a complement after verbs such as be, keep, put, and place. Subject is typically a person, a team, or an emergency-service unit.

Common Mistakes

The doctor is in standby during the night.
The doctor is on standby during the night.
The correct preposition is on, not in.

3. a low-power condition of a television, computer, or similar appliance: the power

3.nounB1
Definition

a low-power condition of a television, computer, or similar appliance: the power supply remains connected, but the device is not fully active and must be woken by pressing a button or remote control.

Example

Leaving the television on standby all night wastes more electricity than many people realise.

phrase: leave [device] on standby

Élise pressed the power button, but the screen stayed black because it was still in standby mode.

collocation: standby mode

Common collocations
  • on standby
  • standby mode
  • standby power
  • in standby
  • leave on standby
  • enter standby
Synonyms
  • sleep mode

    more common for computers and mobile devices; implies the device can wake quickly

  • idle

    describes a device that is on but not actively processing any task

Antonyms
  • active

    the device is fully on and functioning

Grammar Patterns

on standby

leave [device] on standby

in standby mode

Usage Note

Distinguish from noun sense 2 — sense 2 applies to people and organisations, while sense 3 applies only to electronic devices. Home appliances in standby mode still consume a small amount of electricity, sometimes called vampire power.

4. the situation in which a passenger waits at an airport or theatre hoping to get

4.nounB2
Definition

the situation in which a passenger waits at an airport or theatre hoping to get a seat that opens up shortly before departure or the start of a performance, usually at a reduced price.

Example

Ravindra waited on standby for three hours before a seat opened on the Tokyo flight.

phrase: on standby for [flight]

Students with flexible schedules often travel standby because the tickets are cheaper than regular fares.

phrase: travel standby

Common collocations
  • on standby
  • standby passenger
  • standby ticket
  • fly standby
  • travel standby
  • standby list
Synonyms
  • standby basis

    the arrangement under which standby travel operates

  • go-show

    airline industry term for passengers without a reservation who show up and wait

Antonyms
  • confirmed

    a reservation that guarantees a seat

Grammar Patterns

on standby for [flight/performance]

travel/fly standby

Usage Note

Common in airline and theatre contexts. A passenger on standby is not confirmed for a seat until just before departure or showtime. Some airlines allow standby only for flexible or staff travel.

Common Mistakes

I bought a standby ticket and got a seat for sure.
I bought a standby ticket and hoped a seat would become available.
A standby ticket does not guarantee a seat; it only gives the right to wait for one.

5. a discounted ticket offered shortly ahead of a departure or show, usable only if

5.nounB2
Definition

a discounted ticket offered shortly ahead of a departure or show, usable only if a previously booked seat becomes free.

Example

Kian bought a standby for the evening show when a family of four cancelled their seats.

The woman at the counter said standbys are only sold after confirmed passengers have boarded.

countable noun: standbys (plural)

Common collocations
  • buy a standby
  • sell standbys
  • standby for a flight
  • standby for a show
Synonyms
Antonyms

Grammar Patterns

a standby

buy/use a standby

Usage Note

This sense is distinct from noun sense 4 — sense 4 describes the waiting situation, while sense 5 refers to the actual ticket itself. In everyday speech, standby is often short for standby ticket.

Idioms

ready to be used or to take action immediately if necessary. Can refer to people, equipment, or electronic devices depending on context.

The hospital has two ambulances on standby at all times during the holiday weekend.

Do not leave your laptop on standby overnight if you want to save battery life.

standby — adjective

standby — adverb

standby — verb

Word family

Synonym discussion

Sense: noun/1

Standby, backup, reserve, substitute, and stand-in all refer to something kept ready to replace a primary item, but they differ in usage and connotation. Backup is the most general and common term: you can have a backup plan, a backup file, or a backup player, and it works in both everyday and technical contexts. Reserve often implies a stored supply rather than an immediate replacement — a reserve fund is kept for future needs, not for instant swapping. Substitute focuses on the act of replacement itself and is frequently used in sports (substitute player) and education (substitute teacher). Stand-in is almost exclusively about people temporarily filling a role, particularly in entertainment (a stand-in actor holds the position while lighting is adjusted). Standby, by contrast, emphasises readiness for emergency or failure situations more than the other terms do: a standby generator is there because the main one might fail, whereas a backup generator could simply be an alternative. In everyday conversation, "backup" is the safest choice; in technical or preparedness contexts, "standby" is more precise.

backupreservesubstitutestand-in

Common collocations

Nouns

  • standby generator
  • standby battery
  • standby mode
  • standby passenger
  • standby ticket
  • standby list
  • standby crew
  • standby equipment

Adverbs

  • constantly on standby
  • always on standby
  • permanently on standby
  • immediately on standby

Phrases

  • on standby
  • standby basis
  • standby mode
  • put on standby
  • keep on standby
  • fly standby
  • travel standby

Prepositions

Etymology

Old EnglishEnglish

Standby originates from the verb phrase 'stand by', which appeared in Old English as 'standan bī', meaning 'to be near, to be present'. By the 13th century, 'stand by' had developed the sense of 'to support or remain loyal to someone'. The phrase also acquired a nautical meaning ('to stand by the anchor' — to be ready to handle it) by the 17th century. The noun 'stand-by' (later 'standby') emerged in the late 19th century, first referring to a person or thing that could be relied upon. The modern uses — electronic standby mode (early 20th century) and travel standby (mid-20th century) — are 20th-century developments from the core idea of readiness.