A child of a parent's sibling; a nephew or niece of a parent; a child of one's uncle or aunt.
A relative who has with the other person only two grandparents or one grandparent (maternal or paternal) in common, but parents are different.
The stepson of one's parent who is not one's half-brother.
The son of one's stepparent who is not the son of either of one's biological parents.