What is Actio Ex Delicto?

Legal Definition
In the civil and common law. An action of tort; an action arising out of fault, misconduct or malfeasance. Inst 4, 6, 15; 3 Bl. Comm. 117. Ex maleficio is the more common expression of the civil law; which is adopted by Bracton. Inst. 4, 6, 1; Bract, fols. 102, 103.
-- Black's Law Dictionary
Legal Definition
An action founded upon a tort.
-- Ballentine's Law Dictionary