Dictionary
A big dictionary will also give more information about the word. It will explain how it is pronounced. Usually the International Phonetic Alphabet is used for this. It will explain how the word is used. This is not a problem for a word like "hippopotamus", but a word like "put" has so many different meanings that a large dictionary may have a whole page or more to explain how it can be used. It will also explain the origin of the word (e.g. Greek "hippos" horse and "potamus" river).