What is Actio Non Accrevit Infra Sex Annos?

Legal Definition
The name of a plea to the statute of limitations when the defendant insists that the plaintiff's action has not accrued within six years. It differs from non assumpsit in this: non assumpsit is the proper plea to an action on a simple contract, when the action accrues on the promise but when it does not accrue on the promise but subsequently to it, the proper plea is actio non accrevit, &c. Lawes, Pl. in Ass. 733; 5 Binn. 200, 203; 2 Salk. 422; 1 Saund. Rep. 83 n. 2; 2 Saund, 63, b; 1 Sell. N.P. 121.
-- Bouviers Law Dictionary
Legal Definition
The name of the pica of the statute of limitations, when the defendant alleges that the plaintiff's action has not accrued within six years.
-- Black's Law Dictionary
Legal Definition
The action has not accrued within six years.
-- Ballentine's Law Dictionary