graveyoudaoicibaDictYouDict[grave 词源字典]
grave: Modern English has essentially two words grave. Grave ‘burial place’ goes back ultimately to prehistoric Indo-European *ghrebh- ‘dig’, which also produced Latvian grebt ‘hollow out’ and Old Church Slavonic pogreti ‘bury’. Its Germanic descendant had variants *grōb- (source of groove), *grub- (whence grub), and *grab-.

This last formed the basis of *graban, from which have come the verbs for ‘dig’ in most Germanic languages, including German graben, Dutch graven, Swedish gräva, and Danish grave. The English member of the family, grave, is now virtually obsolete as a verb (although its derivative engrave [16] survives); but its nominal relative grave, also formed from *grab-, is still very much with us. Grave ‘serious’ [16] comes via Old French grave from Latin gravis ‘heavy, important’, source also of English gravity and grief.

Its application to a backward-leaning accent (as in è) comes from the original use of such an accent-mark to indicate low or deep intonation.
=> engrave, groove, grub; gravity, grief[grave etymology, grave origin, 英语词源]
grave (n.)youdaoicibaDictYouDict
"excavation in earth for reception of a dead body," Old English græf "grave; ditch, trench; cave," from Proto-Germanic *graban (cognates: Old Saxon graf, Old Frisian gref, Old High German grab "grave, tomb;" Old Norse gröf "cave," Gothic graba "ditch"), from PIE root *ghrebh- (2) "to dig, to scratch, to scrape" (source also of Old Church Slavonic grobu "grave, tomb"); related to Old English grafan "to dig" (see grave (v.)).
"The normal mod. representation of OE. græf would be graff; the ME. disyllable grave, from which the standard mod. form descends, was prob. due to the especially frequent occurrence of the word in the dat. (locative) case. [OED]
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. Grave-side (n.) is from 1744. Grave-robber attested from 1757. To make (someone) turn in his grave "behave in some way that would have offended the dead person" is first recorded 1888.
grave (adj.)youdaoicibaDictYouDict
1540s, "influential, respected; marked by weighty dignity," from Middle French grave (Old French greve "terrible, dreadful," 14c.), from Latin gravis, "heavy, ponderous, burdensome, loaded; pregnant;" of matters, "weighty, important;" of sounds, "deep, low, bass;" figuratively "oppressive, hard to bear, troublesome, grievous," from PIE root *gwere- (2) "heavy" (cognates: Sanskrit guruh "heavy, weighty, venerable;" Greek baros "weight," barys "heavy in weight," often with the notion of "strength, force;" Old English cweorn "quern;" Gothic kaurus "heavy;" Lettish gruts "heavy"). In English, the sense "solemn, sober" is from 1580s; of immaterial things, "important, serious" 1590s. Greek barys (opposed to kouphos) also was used figuratively, of suffering, sorrow, sobbing, and could mean "oppressive, burdensome, grave, dignified, impressive." The noun meaning "accent mark over a vowel" is c. 1600, from French.
grave (v.)youdaoicibaDictYouDict
"to engrave," Old English grafan "to dig, dig up; engrave, carve, chisel" (medial -f- pronounced as "v" in Old English; past tense grof, past participle grafen), from Proto-Germanic *grabanan (cognates: Old Norse grafa "to dig; engrave; inquire into," Old Frisian greva, Dutch graven "to dig, delve," Old High German graban, German graben, Gothic graban "to dig, carve"), from the same source as grave (n.). Its Middle English strong past participle, graven, is the only part still active, the rest of the word supplanted by its derivative, engrave.