Cousin or 1C:
1- Parent's full sibling's child.
2- Person who, in relation to the other person, has zero parents and two grandparents (maternal or paternal) in common.
1- Pibling's child. / Parent's nibling.
2- Person who, in relation to the other person, has zero parents and two grandparents (maternal or paternal) in common.
3- Cousin.
4- 1C.