Relationship, n.
The state of being related by kindred, affinity, or other alliance. Mason.
Shades of meaning
Fernald has no entry of its own for relationship; he lists it under kin.
Where he writes about it:
Kind is broader than kin, denoting the most general relationship, as of the whole human species in mankind, humankind, etc.; kin and kindred denote direct relationship that can be traced through either blood or marriage, preferably the former; either of these words may signify collectively all persons of the same blood or members of the same family, relatives or relations. — from kin
Affinity is relationship by marriage, consanguinity is relationship by blood. — from kin