classify

(verb) arrange or order by classes or categories. Synonyms: class, sort, assort, sort out, separate. Example: "How would you classify these pottery shards--are they prehistoric?."

(verb) declare unavailable, as for security reasons. Example: "Classify these documents."

(verb) assign to a class or kind. Synonyms: relegate. Examples: "How should algae be classified?." "People argue about how to relegate certain mushrooms."