The act of nullifying; a rendering void and of no effect, or no legal effect.
The nullification crisis in U.S. history, confrontation between the state of South Carolina and the federal government in 1832–33 over the former's attempt to declare null and void within the state the federal Tariffs of 1828 and 1832.
Surgical removal of genitals (and sometimes nipples) as a form of body modification; a person who has undergone this surgery is a nullo.
An act or instance of retracting.
A continuous function from a topological space onto a subspace which is the identity on that subspace.
A statement printed or broadcast in a public forum which effects the withdrawal of an earlier assertion, and which concedes that the earlier assertion was in error.