One of the names figuratively given to the Devil. Hence, when the Lord Jesus Christ is said to bruise Satan, it is described under the similitude of "treading on the lion and the adder." (Psalms 91:13) Hence also, as sin is of the devil, the infusion of it into our nature, at the fall, is called in Scripture, adder's poison. (Psalms 140:3. See also Genesis 49:17; Proverbs 23:32)