s as z.

Literally, a defeating; a rendering null; the preventing of the operation of an instrument.

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.

The writing containing a defeasance.

Defeat.