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

The latest scorcher comes after Western Europe recorded its hottest June and July on record, according to Copernicus, the European Union’s climate monitor. — Hanna Ziady, CNN Money, 14 Aug. 2026

The editorial is right that market monitor Joe Bowring told RTO Insider that the state’s 2021 clean energy law played a role in Illinois’ price. — Chicago Tribune, 13 Aug. 2026

Verb

Between 60% and 70% of new Ebola cases are being detected among people who were not already being monitored as contacts, meaning health workers may only discover infections after patients become sick and have had opportunities to expose others. — ABC News, 15 Aug. 2026

Cardiff had their problems under Malaysian businessman Tan but not nearly as many as Wednesday, whom Storch had been advised to monitor 12 months before his eventual takeover. — Philip Buckingham, New York Times, 14 Aug. 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