The Collaborative International Dictionary
Grave wax
Grave \Grave\, n. [AS. gr?f, fr. grafan to dig; akin to D. & OS. graf, G. grab, Icel. gr["o]f, Russ. grob' grave, coffin. See Grave to carve.] An excavation in the earth as a place of burial; also, any place of interment; a tomb; a sepulcher. Hence: Death; destruction.
He bad lain in the grave four days.
--John xi. 17.
Grave wax, adipocere.
Wiktionary
grave wax
n. A waxy substance found on corpses: adipocere.