Funeral
late Middle English: from Old French funeraille, from medieval Latin funeralia, neuter plural of late Latin funeralis, from Latin funus, funer- ‘funeral, death, corpse’.
wiktionary
[1437] Borrowed from Middle French funeraillespl(“funeral rites”), from Medieval Latin fūnerālia(“funeral rites”), originally neuter plural of Late Latin fūnerālis(“having to do with a funeral”), from Latin fūnus(“funeral, death, corpse”), origin unknown, perhaps ultimately from Proto-Indo-European *dʰew-(“to die”). Singular and plural used interchangeably in English until circa 1700. The adjective funereal is first attested 1725, by influence of Middle French funerail, from Latin funereus, from funus.
etymonline
funeral (n.)
"ceremony of burying a dead person," 1510s, probably short for funeral service, etc., from funeral (adj.).
funeral (adj.)
late 14c., "pertaining to the burial of the dead," mid-15c., from Medieval Latin funeralia "funeral rites," originally neuter plural of Late Latin funeralis "having to do with a funeral," from Latin funus (genitive funeris) "funeral, funeral procession, burial rites; death, corpse," a word of uncertain origin, perhaps ultimately from PIE root *dheu- (3) "to die." Singular and plural used interchangeably in English until c. 1700. In Elizabethan times also a verb, "to mourn" (transitive). The classical Latin adjective was funebris.
