half-nephew-in-law Share definition Flag 1. The son-in-law of one's half-sibling. 2. The son of one's spouse's half-sibling. My half-nephew-in-law is a good person. half-nephew-in-law by Elivaldeq November 24, 2019 0 0 Get merch Get the half-nephew-in-law mug. Buy Now — $32.95 See more merch