1) prone to slander, slanderous, accusing falsely
    1a) a calumniator, false accuser, slanderer,
 2) metaph. applied to a man who, by opposing the cause of God, may be
    said to act the part of the devil or to side with him

 Satan the prince of the demons, the author of evil, persecuting good
 men, estranging mankind from God and enticing them to sin,
 afflicting them with diseases by means of demons who take possession
 of their bodies at his bidding.