KJV Dictionary Definition: blasphemy
BLAS'PHEMY, n. An indignity offered to God by words or writing; reproachful, contemptuous or irreverent words uttered impiously against Jehovah.
Blasphemy is an injury offered to God, by denying that which is due and belonging to him, or attributing to him that which is not agreeable to his nature.
In the middle ages, blasphemy was used to denote simply the blaming or condemning of a person or thing. Among the Greeks, to blaspheme was to use words of ill omen, which they were careful to avoid.
1. That which derogates from the prerogatives of God. Mark 2.