Heteronym, Homograph, Homonym, and Homophone

A homograph is a word that has the same spelling as another word, but has a different meaning, such as lead (to go in front of) and lead (a metal). The ending –graph means drawn or written, so a homograph has the same spelling.

Heteronyms are a type of homograph that are also spelled the same and have different meanings, but sound different, such as above or bow (tied with ribbon)
bow (of a boat).

A homophone is a word that has the same sound as another word, but is spelled differently and has a different meaning, such as to, two, and too. The ending –phone means sound or voice, so a homophone has the same pronunciation.

A homonym means either a word that is spelled like another, but has a different sound and meaning (homograph) or a word that sounds like another, but has a different spelling and meaning (homophone).
OR
A word that is spelled and pronounced like another, but has a different meaning (homograph and homophone), like by (near) and buy (to purchase).

Strictly speaking both homographs and homophones are homonyms, but homonyms can be either or both a homograph and homophone. Heteronyms are always homographs, but homographs are not always heteronyms.

Wordology, Used and Used

These two words are a type of heteronym and homograph. They are spelled alike, but are pronounced different and have different meanings.

The first word is an adjective that means previously used or owned, such as a used car. It also means showing wear, as used clothes and utilized for a reason, as an often used tool.

The second definition means accustomed to, and is pronounced yoost, as in, I am not used to being accused.