step-great-nibling Share definition Flag 1. The grandchild of one's stepsibling. 2. The stepgrandchild of one's sibling. My step-great-nibling is a good person. step-great-nibling by Elivaldeq November 24, 2019 0 0 Get merch Get the step-great-nibling mug. Buy Now — $32.95 See more merch