Cay
The English word cay comes from the Spanish word cayo and this from the Taíno word cayo meaning "small island". The English words key and quay (which means wharf) come from the old French kai meaning "sand bank". Because it is a Taíno word, "cay" (and the other forms) are used mainly in the Caribbean, but the type of island is in tropical seas where there are coral reefs.