observation

observation — noun

1. the activity of watching a person, place, or process closely over time, often to

1.nounB2
Definition

the activity of watching a person, place, or process closely over time, often to gather information, monitor a medical condition, or learn how something behaves.

Example

The nurses kept Grandma under observation for two nights after her fall.

collocation: keep [someone] under observation

Dr. Patel learned a lot about elephants through patient observation in Kenya.

collocation: through observation

Common collocations
  • close observation
  • careful observation
  • patient observation
  • under observation
  • direct observation
Synonyms
  • monitoring

    stresses ongoing checking, often technical or medical

  • surveillance

    stronger; suggests secret or security-related watching

  • study

    broader; can include experiments, not just watching

Grammar Patterns

under observation

observation of + noun

Usage Note

Usually uncountable in this sense. Common with prepositions: 'under observation' (being watched, often medically), 'through observation' (by means of watching), and 'observation of [thing]'.

Common Mistakes

The patient was on observation in the hospital.
The patient was under observation in the hospital.
the fixed preposition is 'under', not 'on'.

2. the personal ability to spot small details that other people miss, treated as a

2.nounB2
Definition

the personal ability to spot small details that other people miss, treated as a quality or skill rather than a single act.

Example

Sherlock Holmes is famous for his powers of observation and quick thinking.

fixed phrase: powers of observation

Dr. Yamada tells her interns that strong observation matters as much as textbook knowledge.

Common collocations
  • powers of observation
  • sharp observation
  • keen observation
Synonyms
Antonyms

Grammar Patterns

powers of observation

skill of observation

Usage Note

Refers to a personal skill, not a single watching event. Typical adjectives: 'sharp', 'keen', 'good', 'poor'. Distinguish from sense 1, which names the action itself.

3. a spoken or written comment in which you share what you have noticed, thought, o

3.nounC1
Definition

a spoken or written comment in which you share what you have noticed, thought, or worked out about something.

Example

Aunt Lin made a sharp observation about how the children only fight before dinner.

collocation: make an observation about

After the match, Coach Diaz's final observation was that the team plays better in the rain.

pattern: observation that + clause

Common collocations
  • make an observation
  • an astute observation
  • observation that
  • helpful observations
Synonyms
  • remark

    more casual; a brief spoken comment

  • comment

    neutral and very common; less formal

  • insight

    stresses depth of understanding behind the comment

Grammar Patterns

make an observation

observation that + clause

observation about/on + noun

Usage Note

Countable in this sense; often pluralized ('her observations on the report'). Frequently introduced with 'make an observation' or 'the observation that…'. Slightly more formal than 'comment' or 'remark'.

Common Mistakes

She said an observation about the painting.
She made an observation about the painting.
the standard verb is 'make', not 'say'.

Word family

Synonym discussion

Sense: noun/1

All four words describe watching closely, but the tone and setting differ. 'Observation' is the most neutral and learner-friendly; it covers science, medicine, and everyday noticing — 'the patient is under observation' or 'observation of the stars'. 'Surveillance' sounds heavier and often secret, used for police, security cameras, or spying: 'the building is under surveillance'. 'Monitoring' suggests ongoing technical checking, often with instruments or data: 'monitoring the patient's heart rate' or 'monitoring water quality'. 'Scrutiny' shifts the focus to careful, judging examination, usually of documents, decisions, or people's behaviour: 'the contract came under close scrutiny'. So a child's bedroom can be 'under observation' by a worried parent, but only a suspect's flat is 'under surveillance'.

observation ↗surveillance ↗monitoringscrutiny ↗

Common collocations

Nouns

  • observation deck
  • observation post
  • observation skills
  • powers of observation

Adverbs

Phrases

  • make an observation
  • keep someone under observation
  • based on observation

Prepositions

  • under observation
  • through observation
  • from observation

Etymology

LatinOld FrenchMiddle EnglishEnglish

From Latin 'observatio', meaning a watching or noting, built on 'observare' ('to watch over, attend to'), itself from 'ob-' ('toward') and 'servare' ('to keep, watch'). It entered English in the late 1300s through Old French 'observation', first describing the keeping of laws and customs, and by the 1500s had broadened to its modern senses of careful watching and the comments such watching produces.