The words nicks, nix sound the same but have different meanings and spellings. Why do nicks, nix sound the same even though they are completely different words?
The answer is simple: nicks, nix are homophones of the English language.
Plural form of nick.
Third-person singular simple present indicative form of nick.
Mythology A water sprite of German mythology, usually in human form or half-human and half-fish.
Not so; no.
To forbid, refuse, or veto: Congress nixed the tax hike.
Definitions from Wiktionary, Creative Commons Attribution/Share-Alike License, from The American Heritage® Dictionary of the English Language, 4th Edition and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.