The words loose, luce sound the same but have different meanings and spellings. Why do loose, luce sound the same even though they are completely different words?
The answer is simple: loose, luce are homophones of the English language.
Not fastened, restrained, or contained: loose bricks.
Not taut, fixed, or rigid: a loose anchor line; a loose chair leg.
Free from confinement or imprisonment; unfettered: criminals loose in the neighborhood; dogs that are loose on the streets.
Not tight-fitting or tightly fitted: loose shoes.
The pike, Esox lucius, when fully grown.
Definitions from The American Heritage® Dictionary of the English Language, 4th Edition, from Wiktionary, Creative Commons Attribution/Share-Alike License and Wordnik.
Homophones (literally "same sound") are usually defined as words that share the same pronunciation, regardless of how they are spelled.