falsehood

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

• noun An untrue statement; a lie or an inaccuracy.
• noun The practice of lying.
• noun Lack of conformity to truth or fact; inaccuracy.

from The Century Dictionary.

• noun The fact or quality of being false; falseness; dishonest purpose or intention; treachery; deceitfulness; perfidy: opposed to truthfulness.
• noun That which is false; a false representation in word or deed; an untruth; a lie: as, the tale is a series of falsehoods; to act a falsehood.
• noun False manifestation or procedure; deceitful speech, action, or appearance; counterfeit; imposture; specifically, in law, a fraudulent imitation or suppression of truth to the prejudice of another.
• noun Synonyms Falsehood, Falseness, Falsity; untruth, fabrication, fiction. Instances may be quoted in abundance from old authors to show that the first three words are often strictly synonymous; but the modern tendency has been decidedly in favor of separating them, falsehood standing for the concrete thing, an intentional lie; falseness, for the quality of being guiltily false or treacherous: as, he is justly despised for his falseness to his oath; and falsity, for the quality of being false without blame: as, the falsity of reasoning.

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

• noun Want of truth or accuracy; an untrue assertion or representation; error; misrepresentation; falsity.
• noun A deliberate intentional assertion of what is known to be untrue; a departure from moral integrity; a lie.
• noun Treachery; deceit; perfidy; unfaithfulness.
• noun A counterfeit; a false appearance; an imposture.

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

• noun uncountable The property of being false.
• noun countable A false statement, especially an intentional one; a lie
• noun archaic, rare Mendacity, deceitfulness; the trait of a person who is mendacious and deceitful.

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

• noun the act of rendering something false as by fraudulent changes (of documents or measures etc.) or counterfeiting
• noun a false statement