To reduce to nothing, to destroy, to eradicate.
To render null and void; to abrogate.
To react with antimatter, producing gamma radiation and (for higher-mass reactants, especially composite particles such as protons) lighter particles (such as pions, muons, and neutrinos).
To reject something.
No.
Nothing; nix; often in the phrase "ixnay on ...", indicating something that must not be mentioned, often in Pig Latin