Old English græf "grave, ditch, cave," from Proto-Germanic *graban (cf. Old Saxon graf, Old Frisian gref, Old High German grab "grave, tomb;" Old Norse gröf "cave," Gothic graba "ditch"), from PIE root *ghrebh- "to dig, to scratch, to scrape" (cf. Old Church Slavonic grobu "grave, tomb"); related to grafan "to dig" (see grave (v.)).
From Middle Ages to 17c., they were temporary, crudely marked repositories from which the bones were removed to ossuaries after some years and the grave used for a fresh burial. "Perpetual graves" became common from c.1650. To make (someone) turn in his grave "behave in some way that would have offended the dead person" is first recorded 1888.