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

U.N. weapons monitors and instructors

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 of monitor

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

Driver aids include automatic high-beams, a backup camera, a blind-spot monitor, a cross-traffic alert, a driver-monitoring alert, a lane-departure warning, a lane-keeping assist, a parking aid, and stability-control functionality. —John Scott Lewinski, Robb Report, 8 Apr. 2026

When Stamford High School students arrive at their personal finance class, they’re greeted by a stock ticker and a TV monitor showing the day’s business and financial news. —P.r. Lockhart, Hartford Courant, 8 Apr. 2026

Verb

Additional law enforcement will be deployed to monitor the situation. —Terell Bailey, CBS News, 11 Apr. 2026

Before applying to be a special agent, Canvasser was a civilian employee assigned to the Office of Strategic Information and Intelligence, which monitors and assesses threats to the president and others under Secret Service protection. —Sasha Pezenik, ABC News, 10 Apr. 2026

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