A hydronym (from Greek: ὕδρω, hydrō, "water" and ὄνομα, onoma, "name") is a type of toponym that designates a proper name of a body of water. Hydronyms include the proper names of rivers and streams, lakes and ponds, swamps and marshes, seas and oceans. As a subset of toponymy, a distinctive discipline of hydronymy (or hydronomastics) studies the proper names of all bodies of water, the origins and meanings of those names, and their development and transmission through history.