The words raising, rasing, razing sound the same but have different meanings and spellings. Why do raising, rasing, razing sound the same even though they are completely different words?
The answer is simple: raising, rasing, razing are homophones of the English language.
Present participle of raise.
Elevation.
Nurturing; cultivation; providing sustenance and protection for a living thing from conception to maturity
Recruitment.
Present participle of ease.
To level to the ground; demolish. See Synonyms at ruin.
To scrape or shave off.
Archaic To erase.
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.
If they are spelled the same then they are also homographs (and homonyms); if they are spelled differently then they are also heterographs (literally "different writing").