hearse (n.)

c. 1300 (late 13c. in Anglo-Latin), "flat framework for candles, hung over a coffin," from Old French herse, formerly herce "large rake for breaking up soil, harrow; portcullis," also "large chandelier in a church," from Medieval Latin hercia, from Latin hirpicem (nominative hirpex) "harrow," a rustic word, from Oscan hirpus "wolf," supposedly in allusion to its teeth. Or the Oscan word may be related to Latin hirsutus "shaggy, bristly."

The funeral display is so called because it resembled a harrow (hearse in its sense of "portcullis" is not attested in English before 15c.). Sense extended to other temporary frameworks built over dead people, then to "vehicle for carrying a dead person to the grave," a sense first recorded 1640s. For spelling, see head (n.).