* Homographs are words that are spelled the same but have different meanings and pronunciations.
While "duck" has multiple meanings (the animal, to bend down, to avoid something), there's no other word with the same spelling that has a completely different pronunciation and meaning.
Perhaps you're thinking of a homophone, which is a word that sounds the same but has different spelling and meaning.
* "Duck" and "Duck" are homophones because they sound the same, but the first refers to the animal and the second is the past tense of the verb "to duck."