Pronunciation: (nul'u-fī"), [key]
—v.t., -fied, -fy•ing.
1. to render or declare legally void or inoperative: to nullify a contract.
2. to deprive (something) of value or effectiveness; make futile or of no consequence.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.