category

A group of people or things that share a feature or are treated as the same type.

• Choose a category from the list.
• We divided the entries into three categories.
• Which category does this film belong to?

How to use it: a category of something (This category of birds has long legs.); fall into a category (These books fall into the same category.)

Similar words: group, type, class

Common phrases: age category, different category, category of something, highest category

A mathematical system of objects and arrows linking them, with rules for joining arrows and leaving objects unchanged.

• This category contains only one object.
• The arrows in this category are functions.
• An identity arrow exists for every object in a category.

Common phrases: small category, category theory, category of sets