That serves to classify

Third-person singular simple present indicative form of classify

The state or condition of being classifiable.

plural of classified advertisement

Any of a list of newspaper or website advertisements included with others under a heading describing the category of product or service offered.

(informal) classified advertisement

plural of classified ad

(mathematics) A topological space that is the quotient of a free action (of the specified group) on a weakly contractible space.

plural of classifying space

(mathematics) A set which serves as the codomain of a characteristic function. / (category theory, uncountable) The subobject classifier restricted to the category Set.