Which word names words with identical spellings but different meanings and pronunciations?

Which word names a word that has the opposite meaning of another word?

Which word names a word that sound the same but have different meanings and spellings?

Which word names a word that imitates the sound of an object, such as "buzz" for a bee?

What word describes an unknown person that has done something, such as write a book?

What word means a person after whom something was named, such as Amerigo Vespucci, from whom we get America?

What word means a fictitious name used by authors who want to hide their identities?

What word means a word that has the same meaning as another word?

What word describes the letters PTA meaning Parent Teacher Association?