blasphemy

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

• noun Contemptuous or profane speech or action concerning God or a sacred entity.
• noun An instance of this.
• noun Irreverent or impious action or expression in regard to something considered inviolable or sacrosanct.
• noun An instance of this.

from The Century Dictionary.

• noun In Old Testament usage, any attempt to diminish the reverence with which Jehovah's name was invested as the Sovereign King of the Jews, or to turn the hearts of the people from their complete allegiance to him.
• noun Hence Any impious or profane speaking of God or of sacred things; reproachful, contemptuous, or irreverent words uttered impiously against God or religion.
• noun Blasphemy cognizable by common law is described by Blackstone to be “denying the being or providence of God, contumelious reproaches of our Saviour Christ, profane scoffing at the Holy Scripture, or exposing it to contempt or ridicule”; by Kent as “maliciously reviling God or religion”; and by Chief Justice Lemuel Shaw as “speaking evil of the Deity with an impious purpose to derogate from the Divine Majesty, and to alienate the minds of others from the love and reverence of God.” Blasphemy is punished as a crime or a misdemeanor by the laws of many nations. In the Roman Catholic Church, language irreverent toward the Virgin Mary and the saints is also held to be blasphemy.
• noun Evil speaking or abusive language against anything held sacred: as, “blasphemy against learning,”
• noun An indecent or scurrilous utterance, as distinguished from fair and respectful discussion; grossly irreverent or outrageous language.
• noun A blasphemer; a blasphemous person.
• noun Synonyms Blasphemy, Profanity, agree in expressing the irreverent use of words, but the former is the stronger, and the latter the wider. Profanity is language irreverent toward God or holy things, covering especially all oaths that, literally interpreted, treat lightly the attributes or acts of God. Blasphemy is generally more direct, intentional, and defiant in its impiety, and is directed toward the most sacred things in religion.

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

• noun An indignity offered to God in words, writing, or signs; impiously irreverent words or signs addressed to, or used in reference to, God; speaking evil of God; also, the act of claiming the attributes or prerogatives of deity.
• noun Figuratively, of things held in high honor: Calumny; abuse; vilification.

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

• noun Irreverence toward something considered sacred or inviolable.
• noun The act of insulting or showing contempt or lack of reverence for any religion's deity or deities.
• noun The act of claiming the attributes of a deity.

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

• noun blasphemous language (expressing disrespect for God or for something sacred)
• noun blasphemous behavior; the act of depriving something of its sacred character