sesqui-cousin-uncle Share definition Flag Son of their grandparent’s half-sibling with the other grandparent’s full sibling. My sesqui-cousin-uncle is a good person. sesqui-cousin-uncle by Hgcloziw November 23, 2019 0 0 Get merch Get the sesqui-cousin-uncle mug. Buy Now — $32.95 See more merch