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

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