The "ambiguous" sense of homonymous refers mainly to words that have two or more meanings. In the 1600s, logicians and scientists who wanted to refer to (or complain about) such equivocal words chose a name for them based on Latin and Greek, from Greek hom- ("same") and onyma ("name"). In time, English speakers came up with another sense of homonymous, referring to two things having the same name (Hawaii, the state, and Hawaii, the island, for example). Next came the use of homonymous to refer to homonyms, such as see and sea. There's also a zoological sense. Sheep and goats whose right horn spirals to the right and left horn spirals to the left are said to be homonymous.