“Put them in mind . . .  To speak evil of no man, . . ”
– Titus 3:1, 2
The Greek word representing “to speak evil” is blasphēmeō or blasphemy. blasphemy is to vilify or to speak about impiously.
This word is a derivative of two words. One is to hinder, that is by implication to injure. The other word is to say something which is to cast a rumor which affects the fame of another. It is to say something which is scurrilous, that is, calumnious against man or impious against God.
Scurrilous is: Using the low and indecent language of the meaner sort of people, or such as only the license of buffoons can warrant. Containing low indecency or abuse; mean; foul; vile; obscenely jocular; as scurrilous language
calumny is: Slander; false accusation of a crime or offense, knowingly or maliciously made or reported, to the injury of another; false representation of facts reproachful to another, made by design, and with knowledge of its falsehood;
impious is: Irreverent towards the Supreme Being; wanting in veneration for God and his authority; irreligious; profane. The scoffer at God and his authority is impious. The profane swear is impious.