What is Actio Non?

Legal Definition
Pleading. After stating the appearance and defence, special pleas begin with this allegation, "that the said plaintiff ought not to have or maintain his aforesaid action thereof against him," actio non habere debet. This is technically termed the actio non. 1 Ch. Plead. 531 2 Ch. Plead. 421 ; Steph. Plead. 394.
-- Bouviers Law Dictionary
Legal Definition
In pleading. The Latin name of that part of a special plea which follows next after the statement of appearance and defense, and declares that the plaintiff "ought not to have or maintain his aforesaid action," etc.
-- Black's Law Dictionary
Legal Definition
A statement in a special plea that the plaintiff has no action.
-- Ballentine's Law Dictionary