If you are indeed asking about "too", here's the breakdown:
Homophone: A homophone is a word that sounds the same as another word but has a different meaning and spelling. The homophone for "too" is "two".
Synonym: A synonym is a word that has the same or nearly the same meaning as another word. Some synonyms for "too" are:
* also
* as well
* besides
* in addition
* moreover
Antonym: An antonym is a word that has the opposite meaning of another word. There isn't a single perfect antonym for "too" as its meaning depends on the context. However, depending on the context, some possible antonyms could be:
* not enough
* insufficient
* lacking
Let me know if you had another word in mind, and I'll be happy to help!