imitation

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

• noun The act or an instance of imitating.
• noun Something derived or copied from an original, often in an inferior way.
• noun Repetition of a phrase or melody often with variations in key, rhythm, and voice.
• noun Repetition of a theme in another voice such that each part continues polyphonously.
• adjective Made to resemble another, usually superior material.

from The Century Dictionary.

• noun The act of imitating; an imitating or copying.
• noun That which is made or produced by imitating; hence, in general, a likeness or resemblance; a simulated reproduction or representation; more loosely, a likeness or resemblance in general.
• noun Specifically, in music, the process or act of repeating a melodic phrase or theme, either at a different pitch or key from the original, or in a different voice-part, or with some rhythmic or intervallic modification not so great as to destroy the resemblance.
• Made in imitation; counterfeit; not genuine; copied: as, imitation stone, lace, gold, etc.

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

• noun The act of imitating.
• noun That which is made or produced as a copy; that which is made to resemble something else, whether for laudable or for fraudulent purposes; likeness; resemblance.
• noun (Mus.) One of the principal means of securing unity and consistency in polyphonic composition; the repetition of essentially the same melodic theme, phrase, or motive, on different degrees of pitch, by one or more of the other parts of voises. Cf. Canon.
• noun (Biol.) The act of condition of imitating another species of animal, or a plant, or unanimate object. See Imitate, v. t., 3.

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

• noun The act of imitating.
• noun A copy.

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

• noun something copied or derived from an original
• noun copying (or trying to copy) the actions of someone else
• noun the doctrine that representations of nature or human behavior should be accurate imitations
• noun a representation of a person that is exaggerated for comic effect
• adjective not genuine or real; being an imitation of the genuine article