monitor

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

• watch
• cover

Examples of monitor in a Sentence

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

David Paul Morris | Bloomberg | Getty Images European stocks followed global peers lower on Friday as investors monitor a global sell-off in chipmaking tech names. —Joseph Wilkins, CNBC, 5 June 2026

The captain was flying the aircraft while the first officer monitored the flight instruments during the gusty approach. —Russell Lewis, NPR, 4 June 2026

While Florida maintains a state office to oversee guardians in dependency cases, no such regulatory body exists that specifically licenses, disciplines, or monitors the guardians operating in high-stakes divorce and custody battles. —Shira Moolten, Sun Sentinel, 4 June 2026

Throughout the training period, researchers monitored weekly survey responses alongside wearable-device metrics, including heart rate variability (HRV), sleep quality and recovery readiness. —Samantha Agate, Kansas City Star, 4 June 2026

Word History

Etymology

First Known Use

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