Word
classify
Phoneticsclas·si·fy, stress on the first syllable
US/ˈkɫæsəˌfaɪ/
UK/klˈæsɪfˌaɪ/
Definitions
01to categorize
B2 · Upper Intermediate
v. to put things into groups because they share the same qualities or features.
v. to arrange or assign things to groups or categories according to shared qualities or characteristics.
日本語:分類する※
“Biologists classify animals into different groups based on their physical features.”
“The library system is designed to classify books by subject matter, making it easier for researchers to locate specific academic texts.”
Synonyms
02to make secret
C1 · Advanced Law Formal · Technical
v. to officially decide that a document or information must be kept secret by the government.
v. to designate information or documents as officially secret and accessible only to authorized people.
“The government decided to classify the report to protect national security.”
“The intelligence agency chose to classify the documents for fifty years, citing the need to protect active field agents.”
Synonyms
Antonyms
Collocations
Common phrases and expressions where native English speakers use the word “classify” in context.
Verb
01. classify information into categories
“The librarian helped us classify the information into categories to make it easier to find.”
verb + noun + prep
02. classify the documents as confidential
“The government decided to classify the documents as confidential for security reasons.”
verb + noun + adj
03. classify the species by habitat
“Biologists often classify the species by habitat to understand their behavior.”
verb + noun + prep
Preposition
04. difficult to classify
“Some modern art pieces are difficult to classify because they combine so many different styles.”
adj + infinitive
Adverb
05. broadly classify the data
“We can broadly classify the data into two main groups: qualitative and quantitative.”
adv + verb
06. correctly classify the samples
“The new software was able to correctly classify the samples with 99% accuracy.”
adv + verb
Usage
The verb is transitive and often takes the preposition 'as' when identifying the specific category.
Pitfall
classify into a group
classify as a group
While you can 'classify things into groups', when identifying the category itself, use 'as' (e.g., 'classify it as a mammal').
Real-World Examples
“To understand what makes hot subdwarfs so unusual, one has to picture the standard map astronomers use to classify stars, a diagram where temperature runs along one axis and brightness along the other.” “The European Chemicals Agency classifies the chemical as harmful to aquatic life.” Etymology
From French classifier. By surface analysis, class + -ify.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.
Word family
VERB
- Exam level
- CambridgeCambridgeCambridge English QualificationsThe exam suite from Cambridge University Press & Assessment, from A1 Movers up to C2 Proficiency. The benchmark names double as CEFR labels.B2 FirstIELTSIELTSInternational English Language Testing SystemThe 0–9 band test co-owned by the British Council, IDP, and Cambridge. Used for university entry, work, and migration.5.5–6.5TOEFL iBTTOEFL iBTTest of English as a Foreign Language, Internet-Based TestETS's academic English test, the standard route for US university admissions. Scored 0–120, with a 1–6 scale since 2026.1–6 scale: 4.0–4.572–94TOEICTOEICTest of English for International CommunicationETS's workplace English test, big in Japan and Korea. Listening & Reading scores 10–990 and tops out at C1.785–944
- Frequency
- Frequent
- Level
- B2 · Upper IntermediateOxford
- Updated
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QR code
englishreference.com/q/classify
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「日本語」 data: JMdict (EDRDG), CC BY-SA 4.0