Pronunciation: (nul"u-fi-kā'shun), [key]
1. an act or instance of nullifying.
2. the state of being nullified.
3. (often cap.) the failure or refusal of a U.S. state to aid in enforcement of federal laws within its limits, esp. on Constitutional grounds.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.