* Two-syllable word: This means the word has two distinct sounds.
* Homonym of synonym: This means the word sounds the same as another word, but has a different meaning. The other word is a synonym (meaning the same thing).
* Synonym for oceans (one syllable): The one-syllable synonym for "oceans" is "seas".
Putting it together: The two-syllable word that sounds like "seas" is "seize".
So the answer is seize.