unnatural

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

• adjective Not in accordance with what usually occurs in nature.
• adjective Not included in nature; artificial.
• adjective Deviating from a behavioral or social norm.
• adjective Brutal or unfeeling.
• adjective Stilted, affected, or awkward.

from The Century Dictionary.

• Not natural; contrary to nature; monstrous; especially, contrary to the natural feelings: as, unnatural offenses.
• Acting without the affections of our common nature; not having the feelings natural to humanity; being without natural instincts: as, an unnatural parent.
• Not in conformity to nature; not agreeable to the real character of persons or things; not representing nature; forced; strained; affected; artificial: as, unnatural images or descriptions.
• =Syn. 1-3. Preternatural, etc. See supernatural.
• Artificial, etc. See factitious.

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

• adjective Not natural; contrary, or not conforming, to the order of nature; being without natural traits.

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

• adjective Not natural; supernatural or artificial.
• adjective Not occuring in the environment or atmosphere
• adjective dated Going against nature; perverse.

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

• adjective not normal; not typical or usual or regular or conforming to a norm
• adjective speaking or behaving in an artificial way to make an impression
• adjective not in accordance with or determined by nature; contrary to nature