Grimman

According to the Old English Dictionary:

ic grimme, ðú grimst, he grimmeþ, grimþ,

grimman

pl. grimmaþ; p. gram, grom, pl. grummon; pp. grummen. I. to rage, roar, make a loud noise; fremere :-- Ðú hie grimman meaht gehýran thou mayest hear it [hell] rage, Cd. 37; Th. 49, 17; Gen. 793. Hwæl-mere hlúde grimmeþ the whale-mere [the sea] rages loudly, Exon. 101 a; Th. 382, 3; Rä. 3, 5. [Cf. O. Sax. grimmid the gróto séo.] II. to run with haste, hasten; properare, currere, festinare :-- Gúþmóde grummon the warlike of mind hastened, Beo. Th. 617; B. 306. [So Grein translates the verb, but may not the word be taken more nearly in the sense of the preceding passages 'loud and fierce was their shout?'] grimman