duplication

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

• noun The act or procedure of duplicating.
• noun The condition of being duplicated.
• noun A duplicate; a replica.
• noun The occurrence of a repeated section of genetic material in a chromosome.
• noun The formation of such a duplication.

from The Century Dictionary.

• noun The act of duplicating, or of making or repeating something essentially the same as something previously existing or done.
• noun In arithmetic, the multiplication of a number by two.
• noun A folding; a doubling; also, a fold: as”, the duplication of a membrane.
• noun In physiology, the act or process of dividing into two by natural growth or spontaneous division.
• noun In music, the process or act of adding the upper or lower octaves or replicates to the tones of a melody or harmony. See double, n. and verb
• noun In botany, same as chorisis.
• noun In admiralty law, a pleading on the part of the defendant in reply to the replication.
• noun Eccles., the celebration of the mass or eucharist twice by the same priest on the same day.

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

• noun The act of duplicating, or the state of being duplicated; a doubling; a folding over; a fold.
• noun (Biol.) The act or process of dividing by natural growth or spontaneous action.
• noun (Math.) the operation of finding a cube having a volume which is double that of a given cube.

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

• noun The act of duplicating, or the state of being duplicated; a doubling; a folding over; a fold.
• noun The act or process of dividing by natural growth or spontaneous action; as, the duplication of cartilage cells.

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

• noun a copy that corresponds to an original exactly
• noun the act of copying or making a duplicate (or duplicates) of something