The crossword solution for the term 'Ring Cycle Goddess' is ERDA, which is a four-letter word. ERDA is the goddess of Earth in Norse mythology and is featured in Richard Wagner's famous opera cycle, Der Ring des Nibelungen (The Ring of the Nibelung). She is the daughter of the primordial being Ymir and is married to the god Wotan. ERDA is also known as Jord, Fjorgyn, Hlodyn, and Mother Earth.