Homophones are words that sound the same but have different meanings and spellings. Since "syntax" is a fairly unique word, there's no other word that sounds exactly the same.
However, there are words that are close in pronunciation but are not true homophones:
* Sin tax: This refers to a tax levied on goods considered harmful or luxurious.
* Syntex: This is a word that refers to a specific company, Syntex Corporation, which was a pharmaceutical company.
While these words sound similar to "syntax," they are distinct words with different meanings.