Heolstor-cófa

According to the Old English Dictionary:

an;

heolstor-cófa

m. A dark, concealed chamber, grave :-- Deáþræced heleþa heolstorcófan onhliden, weorþaþ the death houses, the graves of men shall be uncovered, Exon. 56 b; Th. 200, 31; Ph. 49. heolstor-cofa