second co-cousin-in-law Share definition Flag The grandchild-in-law of one's grandparent-in-law's sibling. My second co-cousin-in-law is a good person. second co-cousin-in-law by Elivaldeq November 24, 2019 0 0 Get merch Get the second co-cousin-in-law mug. Buy Now — $32.95 See more merch