monitor

1 of 2

noun

mon·​i·​tor ˈmä-nə-tər 

1

a

: a student appointed to assist a teacher

b

: one that warns or instructs

monitors and instructors for troops green in the art of war

—New York Times

c

: one that monitors or is used in monitoring: such as

(1)

: an electronic device with a screen used for display (as of television pictures or computer information)

(2)

: a device for observing a biological condition or function

a heart monitor

2

: monitor lizard

3

[Monitor, first ship of the type]

a

: a heavily armored warship formerly used in coastal operations having a very low freeboard and one or more revolving gun turrets

b

: a small modern warship with shallow draft (see draft entry 1 sense 8) for coastal bombardment

4

: a raised central portion of a roof having low windows or louvers for providing light and air

monitorial

ˌmä-nə-ˈtȯr-ē-əl 

adjective

monitorship

ˈmä-nə-tər-ˌship 

noun

monitor

2 of 2

verb

monitored; monitoring ˈmä-nə-t(ə-)riŋ 

transitive verb

: to watch, keep track of, or check usually for a special purpose

Nurses monitored the patient's heart rate.

Synonyms

Verb

• watch
• cover

Examples of monitor in a Sentence

Noun

They watched the press conference on a video monitor in a back room.

We put a baby monitor in the nursery.

U.N. weapons monitors and inspectors.

Verb

Nurses constantly monitored the patient's heart rate.

We're in a good position to monitor and respond to customer concerns.

Government agents have been monitoring the enemy's radio communications.

Recent Examples on the Web

Noun

In the quiet hush of the neonatal intensive care unit at Shahjahanpur Medical College, the only constant sound was the monotone of the heart monitor, its low hum keeping watch over the baby sleeping inside the sterile incubator. —Aishwarya S. Iyer, CNN Money, 16 Oct. 2025

Some of Michigan's largest airports are showing a politicized message from Homeland Security Secretary Kristi Noem that many say violates the Hatch Act on monitors in their facilities, but not all Michigan airports are doing so. —Dan Basso, Freep.com, 15 Oct. 2025

Verb

Such caveats underscore the weakness of compliance monitoring snapshots in capturing the complex pressures and administrative barriers constraining workers’ ability to exercise their rights on a day-to-day basis. —Sourcing Journal, 15 Oct. 2025

After all, Coe and River had been monitoring the scene for the candidate’s safety and this was an accident. —Scott Tobias, Vulture, 15 Oct. 2025

Word History

Etymology

Noun and Verb

Latin, one that warns, overseer, from monēre to warn — more at mind

First Known Use

Noun

1530, in the meaning defined at sense 1a

Verb

1924, in the meaning defined above

Phrases Containing monitor

• baby monitor
• hall monitor
• monitor lizard

Kids Definition

monitor

1 of 2 noun

mon·​i·​tor ˈmän-ət-ər 

1

a

: a student appointed to assist a teacher

b

: a person that warns or instructs

c

: one that monitors or is used in monitoring

especially : a video screen used for display (as of television pictures or computer information)

2

: monitor lizard

3

a

: a heavily armored warship having low sides and revolving guns that was used against shipping in harbors and in river patrol

b

: a gunboat used to bombard coastal areas and riverbanks

monitor

2 of 2 verb

monitored; monitoring ˈmän-ət-ə-riŋ 

ˈmän-ə-triŋ

: to watch, observe, or check for a special purpose

monitor a broadcast for sound quality

Medical Definition

monitor

1 of 2 noun

mon·​i·​tor ˈmän-ət-ər 

: one that monitors

especially : a device for observing or measuring a biologically important condition or function

a heart monitor

monitor

2 of 2 transitive verb

monitored; monitoring ˈmän-ət-ə-riŋ, ˈmän-ə-triŋ 

1

: to watch, observe, or check closely or continuously

monitor a patient's vital signs

2

: to test for intensity of radiations especially if due to radioactivity