classify
gb/klˈæsɪfˌaɪ/ us/klˈæsɪfˌaɪ/
B1
English
~ 3900
Senses
0 senses
Verb
B1
action
1
Arrange into groups or categories
To put people or things into groups because they are similar in some way.
Usage pattern:
to classify [something] as [category]
Common mistake:
Learners sometimes confuse 'classify' with 'identify'. 'Classify' means to put into a category, while 'identify' means to recognize what something is.
Synonyms
categorize (More common in everyday speech; interchangeable in many contexts.)
|
sort (Often used for simpler or more physical arrangements.)
Antonyms
mix (Opposite in the sense of not separating into categories.)
|
confuse (Opposite in the sense of making categories unclear.)
Collocations
classify information
|classify data
|classify documents
|classify animals
|classify as
Themes
organization
|science
|education
|work
|core_vocabulary
Examples
- Scientists classify animals into groups such as mammals, birds, and reptiles.
- The library system classifies books by subject.
- The teacher asked the students to classify the shapes by the number of sides.
- The company classifies its products based on price range.
- Historians classify ancient artifacts according to their origin.
Learner examples
- We classify the clothes by color.
- The teacher will classify the papers.
- They classify cars by size.
- Classify these fruits into two groups.
- We can classify animals by where they live.
Verb
technical
B2
action
2
Mark information as secret or restricted
To say officially that some information must be kept secret for security reasons.
Usage pattern:
to classify [information/document] as [security level]
Common mistake:
Learners may confuse this meaning with 'classify' for categorizing. In this sense, it is about secrecy, not grouping.
Synonyms
restrict (General term for limiting access; not specific to security classification.)
|
confidentialize (Rare and formal; means to make confidential.)
Antonyms
declassify (Officially remove the secret status from something.)
Collocations
classify a document
|classify information
|classify data as confidential
|classified material
Themes
government
|security
|law
|business
|communication
Examples
- The government decided to classify the report for national security reasons.
- Military officials classified the mission details as top secret.
- The agency classified the files to protect sensitive information.
- They classified the data to prevent leaks.
- All communications from that period were classified immediately.
Learner examples
- The army classified the plan.
- They classified the letter as secret.
- The police classified the photo.
- We must classify these files before sending them.
- The report is classified by the government.
Grammar
Dictionary form
classify
IPA
GB/klˈæsɪfˌaɪ/
US/klˈæsɪfˌaɪ/
Syllables & stress
clas - si - fy (3 syllables)
Stress on 1st syllable (clas)
Word forms
Verb
- Base: classify
- 3rd Person Singular: classifies
- Present Participle: classifying
- Past: classified
Word family
Forms
Core family
class
noun A1
classification
noun B1
Related words
Negative and opposite forms
unclassified
adjective
misclassify
verb
Advanced or less common
unclassifiable
adjective
declassify
verb C1
Expressions
classify as
1/klˈæsɪfˌaɪ ˈæz/
fixed phrase
Put something in a category
To say that something belongs to a certain group or type.
Examples
- Many experts classify this bird as endangered.
- I would classify his style as modern.
- The law classifies this act as a crime.
highly classified
1/hˈaɪli klˈæsɪfˌaɪd/
fixed phrase
technical
Very secret in official terms
Having a very high level of official secrecy.
Examples
- The details of the operation are highly classified.
- She works with highly classified documents.