/di fee"zeuhns/ , n. Law.
1. a rendering null and void.
2. a condition on the performance of which a deed or other instrument is defeated or rendered void.
3. a collateral deed or other writing embodying such a condition.
[ 1400-50; late ME defesance defesaunce, OF defesance, equiv. to desfes- (ptp. s. of desfaire to undo; see DEFEAT) + -ance -ANCE ]