Nix/nɪks/ Definition 1 of 3Pro Tip 1/3Often Negative Used to express prohibition, denial, or refusal, usually in a negative or unwelcoming context. He wanted to go out, but I had to nix that idea. Pro Tip 2/3Formal Rejection Can be used in formal situations like meetings or official documents to indicate a strong 'no'. The board nixed the merger with a unanimous vote. Pro Tip 3/3Casual Tone Even in formal settings, using 'nix' can make the tone feel more casual or conversational. We'll have to nix this agenda item due to time constraints.