The words gamin, gammon sound the same but have different meanings and spellings. Why do gamin, gammon sound the same even though they are completely different words?
The answer is simple: gamin, gammon are homophones of the English language.
An often homeless boy who roams about the streets; an urchin.
A victory in backgammon reached before the loser has succeeded in removing a single piece.
To defeat in backgammon by scoring a gammon.
Misleading or nonsensical talk; humbug.
See Shelta.
Definitions 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").