stepcousin

noun3

1. •
   A nephew or niece of someone's stepparent; a child of someone's stepaunt or stepuncle (in the sense of a sibling of someone's stepparent).
2. •
   A stepchild of someone's aunt or uncle; a stepnephew or stepniece (in the sense of a stepchild of someone's sibling) of someone's parent.
3. •
   A child of someone's stepaunt or stepuncle (in the sense of a stepsibling of someone's parent); a stepnephew or stepniece (in the sense of a child of someone's stepsibling) of someone's parent.