Dégol-ful

According to the Old English Dictionary:

dégol-ful

adj. Full of secret, mysterious; secrēti plēnus, mystĭcus :-- Ic míðan sceal dégolfulne dóm mínne I must conceal my mysterious power, Exon. 127 b; Th. 491, 14; Rä. 80, 14. degol-ful