What Is this House Plant?

I'm having trouble identifying this large vining plant. I've always just called it a giant pothos, but that doesn't really seem to be a thing according to the interwebs. Ive taken a large cutting of it from my mother's mother (har har) and have it in water hoping it will root. If you could provide proper identification for this beauty and/or tips for rooting it, I'd be much obliged. I'd be quite sad if I destroyed such a magnificent specimen due to my ignorance.