Homophones are words that sound the same but are spelled differently and have different meanings.
While "until" is a very common word, there aren't any other words that sound exactly the same.
However, depending on the context, you could use similar-sounding words like:
* Untill (archaic spelling)
* Untilled (meaning not cultivated)
* Untilted (meaning not tilted)
These words are not exact homophones, but they might fit in certain situations if the meaning is close enough.