Lat. He detains. In old English law. A species of action of debt, which lay for the specific recovery of goods, under a contract to deliver them. 1 Reeves, Eng. Law, 159.In pleading. An action of debt is said to be in the detinet when it is alleged merely that the defendant witholds or unjustly detains from the plaintiff the thing or amount demanded.An action of replevin is said to be in the detinet when the defendant retains possession of the property until after judgment in the action. Bull. N. P. 52; Chit. PI. 145.