monitor

monitor — noun

IPA/ˈmɒnɪtə(r)/
KK[mˈɑnətɚ]IPA/ˈmɑːnɪtər/
  • monitorsingular
  • monitorsplural

1. Someone assigned to keep a close watch on an activity, process, or event and rep

1.nounB2
Definition

Someone assigned to keep a close watch on an activity, process, or event and report their findings, often to check that rules or standards are met.

Example

UN monitors arrived at the polling station before dawn to observe the election.

compound: UN monitor / election monitor

Walid worked as a safety monitor at the construction site last summer.

compound: safety monitor

Common collocations
  • election monitor
  • UN monitor
  • safety monitor
  • independent monitor
  • ceasefire monitor
Synonyms
  • observer

    More general; an observer watches without necessarily being assigned to report

  • supervisor

    Focuses on overseeing people's work rather than watching a process

  • inspector

    Implies checking for faults or quality standards, often in a formal setting

Grammar Patterns

election monitor

UN monitor

safety monitor

Usage Note

Commonly appears in compound job titles such as 'election monitor', 'safety monitor', 'UN monitor'.

Common Mistakes

The teacher monitored the exam room for cheaters.
The teacher watched the exam room for cheaters.
For a short, physical observation in a room, 'watch' or 'supervise' is more natural than 'monitor'.

2. A device or machine that regularly checks, measures, or records information such

2.nounB2
Definition

A device or machine that regularly checks, measures, or records information such as heart rate, air quality, or system performance.

Example

The heart rate monitor showed that Indra's pulse stayed steady throughout the race.

compound: heart rate monitor

Air quality monitors near the factory recorded unsafe levels of smoke every morning.

compound: air quality monitor

Common collocations
  • heart rate monitor
  • baby monitor
  • air quality monitor
  • blood pressure monitor
  • computer monitor
Synonyms
  • sensor

    A sensor detects changes but does not necessarily record or display them

  • detector

    Focuses on identifying the presence of something (e.g. smoke detector), not ongoing measurement

Grammar Patterns

heart rate monitor

baby monitor

air quality monitor

Usage Note

The noun describing what is being measured (e.g. 'heart rate', 'baby', 'air quality') always comes before 'monitor'.

3. A screen that displays text, images, or video from a computer or other electroni

3.nounA2
Definition

A screen that displays text, images, or video from a computer or other electronic device.

Example

Henrik adjusted his monitor to a higher position to reduce neck pain.

Mauricio connected his laptop to a large monitor for the video meeting.

monitor as external display

Common collocations
  • computer monitor
  • external monitor
  • flat-screen monitor
  • 27-inch monitor
  • LCD monitor
Synonyms
  • screen

    More general term for any display surface; 'monitor' is specifically a computer display

  • display

    More technical or formal; used in product specifications and technical writing

Grammar Patterns

monitor + screen size (e.g. 27-inch monitor)

Usage Note

For phones and tablets, 'screen' is more common than 'monitor'. 'Monitor' is the standard term for desktop and laptop computer displays.

Common Mistakes

I cracked the monitor of my phone.
I cracked the screen of my phone.
For phones and tablets, use 'screen', not 'monitor'.

4. A student who is chosen to carry out specific responsibilities in class, like co

4.nounB1
Definition

A student who is chosen to carry out specific responsibilities in class, like collecting assignments, helping the teacher, or keeping the hallway quiet.

Example

The class monitor collected the homework and placed it on the teacher's desk.

compound: class monitor

Felix served as the hall monitor during the final exams to keep the corridor quiet.

compound: hall monitor

Common collocations
  • class monitor
  • hall monitor
  • lunch monitor
  • playground monitor
Synonyms
  • prefect

    A more senior student role in British schools with broader authority than a monitor

  • helper

    Less formal and not specific to school structures

Grammar Patterns

class monitor

hall monitor

lunch monitor

Usage Note

This sense is most common in British and Commonwealth school systems. In Taiwan, the equivalent role is 風紀股長 (classroom discipline monitor).

5. A large tropical reptile with a long body, strong legs, and a forked tongue, fou

5.nounC1
Definition

A large tropical reptile with a long body, strong legs, and a forked tongue, found in Africa, Asia, and Australia.

Example

A massive monitor lizard was basking on a rock near the riverbank.

full form: monitor lizard

Christopher saw a monitor lizard climb quickly up a tree in the national park.

Common collocations
  • monitor lizard
  • Komodo dragon
  • water monitor
  • Nile monitor
Synonyms
  • goanna

    Australian term for monitor lizards, common in Australian English

Grammar Patterns

monitor lizard

Usage Note

Often used in the two-word compound 'monitor lizard' to distinguish from the other meanings of 'monitor'. The general term 'monitor' alone is usually clear from context.

monitor — verb

IPA/ˈmɒn.ɪ.tər/
KK[mˈɑnətɚ]IPA/ˈmɑː.nə.t̬ɚ/

Word family

Synonym discussion

Sense: verb/1

All five words involve watching something, but they differ in purpose and intensity. 'Monitor' implies systematic, ongoing checking for changes or problems — you monitor a patient's vital signs or a company's performance. 'Observe' is broader and more passive; you can observe birds in a park without any goal. 'Track' focuses on following movement or progress over time — you track a shipment or a runner's lap times. 'Supervise' and 'oversee' both involve authority over people or work, but 'supervise' is more hands-on (supervising a trainee) while 'oversee' suggests a higher-level management role (overseeing the entire project). For example: A nurse monitors a patient's recovery hourly; a supervisor watches the nurse's work; a hospital director oversees the whole department.

monitor ↗observe ↗track ↗supervise ↗oversee ↗

Common collocations

Nouns

Adverbs

Phrases

  • keep under close observation
  • on the lookout for

Prepositions

  • for signs of change

Etymology

LatinEnglish

From Latin 'monere' meaning 'to warn', via 'monitor' ('one who warns'). The word entered English in the 16th century for a person who gives advice or warnings. The meaning expanded to devices that warn or track information in the 20th century with the rise of electronic technology. The computer screen sense appeared in the 1970s. The 'monitor lizard' sense comes from the lizard's supposed habit of giving warnings about crocodiles nearby.