The term 'Blue Moon' is a RARE phenomenon that occurs when two full moons appear in the same calendar month. The crossword solutions for this term are RARE (4 letters), ODOM (4 letters), AGE (3 letters), ETERNITY (8 letters), AGES (4 letters), and RARELY (6 letters). RARE and RARELY refer to the infrequency of the occurrence of a Blue Moon, while ODOM and AGES refer to the length of time it takes for a Blue Moon to happen again. Finally, AGE and ETERNITY allude to the timelessness of the event.