Disintegrate will kill a Half-Orc if it reduces to 0, but what about massive damage?

@JeremyECrawford we know that Disintegrate will kill a Half-Orc if it reduces them to 0, but what about massive damage? My reading is that the Half-Orc may use their Relentless Endurance trait to stay at 1 hit point instead, my friend says they die immediately. Who's correct?

— Jeremy Graten (@DockOfManyBards) October 11, 2018

Massive damage kills you outright, which is another way of saying instantly (see "Player's Handbook," p. 197).

The half-orc's Relentless Endurance trait says it doesn't work if you're killed outright. #DnD https://t.co/NL9nNZY5c7

— Jeremy Crawford (@JeremyECrawford) October 11, 2018

Thank you for the swift reply. The Half-Orc’s Relentless Endurance trait won’t save them, but would a Shadow Magic Sorcerer’s Strength of the Grave feature as that does not say “die outright” ? That's correct.

— Jeremy Crawford (@JeremyECrawford) October 11, 2018