Emily Dickinson Lexicon

DE-FEAS'ANCE, n. [s as z; Norm. defesance; Fr. defesant, from defaire, to undo; de and faire, L. facio.]

1. Literally, a defeating; a rendering null; the preventing of the operation of an instrument.
2. In law, a condition, relating to a deed, which being performed, the deed is defeated or rendered void; or a collateral deed, made at the same time with a feoffment or other conveyance, containing conditions, on the performance of which the estate then created may be defeated. A defeasance, on a bond, or a recognizance, or a judgment recovered, is a condition which, when performed, defeats it. A defeasance differs from the common condition of a bond, in being a separate deed, whereas a common condition is inserted in the bond itself. – Blackstone.
3. The writing containing a defeasance.
4. Defeat. [Obs.] – Spenser.