A naiad is a nature spirit from ancient Greek mythology who lives in and protects freshwater places like rivers, streams, springs, and lakes. The Greeks imagined naiads as beautiful young women who embodied the life and spirit of their particular body of water. Each naiad was bound to her specific water source: a spring naiad lived in and cared for her spring, and if that spring dried up, she would fade away too.

Unlike sea nymphs called nereids who lived in the ocean, naiads were freshwater spirits. Ancient Greeks believed naiads could grant wishes, heal the sick with their waters, or become angry if someone polluted their streams. In many Greek myths, heroes would encounter naiads at springs or riverbanks, and some naiads fell in love with mortals or gods.

Today, scientists use naiad as a name for certain freshwater mussels, continuing the connection between the word and freshwater creatures. You might also encounter naiads in fantasy books and games as magical water beings, though modern versions sometimes stray from the original Greek stories.