classification

from The American Heritage® Dictionary of the English Language, 5th Edition.

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

from The Century Dictionary.

• noun In shipbuilding, the assignment to and arrangement of merchant vessels in classes by registration societies. See class, n., 8.
• noun 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.

from the GNU version of the Collaborative International Dictionary of English.

• noun 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.
• noun (Science) See under Artifitial.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun 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.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

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