plural monitors
1
: a device that is used for showing, watching, or listening to something: such as
a
: a device that shows information or images on a screen
a computer monitor
a television monitor
They watched the press conference on a video monitor in a back room.
b
: a device that is used to listen to sounds being made in another room
We put a baby monitor in the nursery.
c
: a device that shows and records information about a condition or function of the body
a heart monitor
2
: a student who helps the teacher at a school
(US) He was chosen to be a hall monitor. [=a student who watches the hallways for bad behavior]
3
: a person who has the job of checking or watching some activity or behavior
U.N. weapons monitors and inspectors
monitors; monitored; monitoring
: to watch, observe, listen to, or check (something) for a special purpose over a period of time
Nurses constantly monitored the patient's heart rate.
We're in a good position to monitor and respond to customer concerns.
She's been able to monitor [=keep track of] his progress.
Government agents have been monitoring the enemy's radio communications.
Cite this Entry
“Monitor.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/monitor. Accessed 22 Jun. 2026.
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