Un-grund

According to the Old English Dictionary:

un-grund

adj. Bottomless, boundless, immense :-- Ðæs heriges hám eft ne com ealles ungrundes ǽnig of that host, all boundless as it was, not one came home again, Cd. Th. 209, 32; Exod. 508. [Cf. Icel. ú-grunnr not shallow; ú-grynni; n. boundlessness, in phrases like ú-grynni hers, liðs, manna.] un-grund