Lat He undertook; he promised. A promise or engagement by which one person assumes or undertakes to do some act or pay something to another. It may be either oral or in writing, but is not under seal. It is express if the promisor puts his engagement in distinct and definite language; it is implied where the law infers a promise (though no formal one has passed) from the conduct of the party or the circumstances of the case. In practice. A form of action which lies for the recovery of damages for the non-performance of a parol or simple contract; or a contract that is neither of record nor under seal. 7 Term, 351; Ballard v. Walker, 3 Johns. Cas. (N. Y.) 60. The ordinary division of this action is into (1) common or indebitatus assumpsit, brought for the most part on an implied promise; and (2) special assumpsit, founded on an express promise. Steph. PI. 11, 13. The action of assumpsit differs from trespass and trover, which are founded on a tort, not upon a contract; from covenant and debt, which are appropriate where the ground of recovery is a sealed instrument, or special obligation to pay a fixed sum; and from replevin, which seeks the recovery of specific property, if attainable, rather than of damages.