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
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
monitored; monitoring
ˈmä-nə-t(ə-)riŋ
: to watch, keep track of, or check usually for a special purpose
Nurses monitored the patient's heart rate.
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
Christine Pelisek, PEOPLE, 2 Apr. 2026
Heart rate monitor Fitness enthusiasts will embrace the heart rate monitor.
—Bestreviews, Chicago Tribune, 2 Apr. 2026
Ameya Paleja, Interesting Engineering, 3 Apr. 2026
The Real-Time Crime Center expanded the department’s security camera network to enable officers to monitor crime in real time in 2024.
—Stella Canino-Quinones, Baltimore Sun, 3 Apr. 2026
See All Example Sentences for monitor
Examples are automatically compiled from online sources to
show current usage.
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Opinions expressed in the examples do not represent those of Merriam-Webster or its editors.
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Noun
Roediger allegedly saw the woman speaking with her boyfriend in the front yard on her bedroom security monitor and then went to the front door where a verbal altercation ensued.
—Christine Pelisek, PEOPLE, 2 Apr. 2026
Heart rate monitor Fitness enthusiasts will embrace the heart rate monitor.
—Bestreviews, Chicago Tribune, 2 Apr. 2026
Verb
To evaluate detector performance, the researchers first measured the incoming microwave signal by monitoring changes in the device’s energy levels.
—Ameya Paleja, Interesting Engineering, 3 Apr. 2026
The Real-Time Crime Center expanded the department’s security camera network to enable officers to monitor crime in real time in 2024.
—Stella Canino-Quinones, Baltimore Sun, 3 Apr. 2026
See All Example Sentences for monitor
Cite this Entry
“Monitor.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/monitor. Accessed 5 Apr. 2026.
Copy CitationKids 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
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
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