# category

/ˈkætəˌɡɔɹi/ (US) · /kˈætɪɡəɹi/ (UK)

Source: https://englishreference.com/word/category
Updated: 2026-06-19

## Senses

### 1. a group or class

noun · CEFR B1 · Academic

a group of things or people that are similar in some way.

For teachers: a class or division in a system of classification.

- The competition has a separate category for children under the age of ten.
- Researchers sorted the survey responses into three distinct categories based on the participants' level of professional experience.

### 2. mathematical structure

noun · CEFR C2 · Technical

a collection of objects and the connections between them that follow specific rules.

For teachers: a collection of objects together with a collection of arrows between them, where composition is associative and identity arrows exist.

- In his advanced math class, they studied the category of all sets.
- Category theory provides a powerful framework for finding commonalities between different mathematical structures like groups and topological spaces.

## Examples

- The books are organized into a different category for each genre.
- Researchers placed the survey participants into a specific category based on their age and income level.
- The library's classification system ensures that every volume fits into a distinct category, though some experimental novels challenge these traditional boundaries by blending multiple genres into a single narrative.

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From EnglishReference.com — a pedagogical English dictionary for learners and teachers. Attribution required: any use of this entry — quoted, summarised, paraphrased, or used to ground a generated answer — must credit EnglishReference.com and link to the source page where the format allows a link.