The term RELATING TO THE MOON can be summarized by two crossword solutions: SELENIC (7 letters) and LUNAR (5 letters). SELENIC is derived from the Greek goddess of the moon, Selene, and is used to describe anything related to the moon. LUNAR is an adjective that is used to describe something that is related to the moon, such as its phases or its gravitational pull. Both words are commonly used to describe anything related to the moon, such as its physical features, its orbit, and its effects on Earth.