Hádor

According to the Old English Dictionary:

es;

hádor

m. n [?] The clear, serene sky; serenum :-- Under heofenes hádor under heaven's serene, Beo. Th. 832; B. 416. [Cf. O. H. Ger. heiteri serenum : Icel. heið the brightness of the sky.] Cf. rodor, and see hádor; adj. hador