classification

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The act, process, or result of classifying.
2. n. A category or class.
3. n. Biology The systematic grouping of organisms into categories on the basis of evolutionary or structural relationships between them; taxonomy.

Century Dictionary and Cyclopedia

1. n. The act of forming a class or of dividing into classes; the act of grouping together those beings or things which have certain characters in common; distribution into sets, sorts, or ranks; taxonomy. In natural history classification has been made on two principles, distinguished as the natural and the artificial: the former aiming to arrange all known plants or animals according to their resemblances, and degrees of resemblance, in the whole plan of their structure; the latter arranging them by some one or more points of resemblance or difference, as may be most convenient and easy, and without regard to other considerations. The widest divisions in zoology are called subkingdoms; subkingdoms are divided into phyla or classes, classes into orders, orders into families, families into genera, genera into species, and species into varieties. There are also intermediate divisions, as subclass, superorder, suborder, subfamily, etc. In botany the same divisions are used as in zoology, except that orders and families are identical, and the term phylum is not used. See animal kingdom, under animal, and class, 5.
2. n. In shipbuilding, the assignment to and arrangement of merchant vessels in classes by registration societies. See class, n., 8.

Wiktionary

1. n. The act of forming into a class or classes; a distribution into groups, as classes, orders, families, etc., according to some common relations or attributes.

GNU Webster's 1913

1. n. The act of forming into a class or classes; a distribution into groups, as classes, orders, families, etc., according to some common relations or affinities.

WordNet 3.0

1. n. the basic cognitive process of arranging into classes or categories
2. n. a group of people or things arranged by class or category
3. n. restriction imposed by the government on documents or weapons that are available only to certain authorized people
4. n. the act of distributing things into classes or categories of the same type