Latin.He undertook. 1 An enforceable promise or undertaking that is not under seal. 2An action for expectation damages caused by the breach of a promise or a contract not under seal. express assumpsit. Such a promise that is made orally or in writing. implied assumpsit. Such a promise that is presumed due to individual's conduct or the circumstances of the situation. general assumpsit. An action based the breach of an implied promise or contract to pay a debt. Also called common assumpsit. sp...