Mumtie Share definition Flag A auntie who don't have their own children but looks after there siblings children for a length of time or permanently. I live with my auntie and she is like a mum to me. She is my mumtie. Mumtie by Natmommyvegas January 11, 2023 0 0 Get merch Get the Mumtie mug. Buy Now — $32.95 See more merch