As, Or Asa (Norse, plur. Aesir; Ger. plur. Asen), in northern mythology, a member of the ruling race of gods, 12 male and 12 female, including Odin, Thor, Baldur, Freyr, Frigga, Freyja, Idunna, Eira, and Saga, who dwelt in Asgard. (See Mythology.)