Relationship by alliance (2 Chronicles 18:1) or by marriage (1 Kings 3:1). Marriages are prohibited within certain degrees of affinity, enumerated Leviticus 18:6-17. Consanguinity is relationship by blood.

Noah Webster's New International Dictionary of the English Language

1. (n.) Relationship by marriage (as between a husband and his wife's blood relations, or between a wife and her husband's blood relations); -- in contradistinction to consanguinity, or relationship by blood; -- followed by with, to, or between.

2. (n.) Kinship generally; close agreement; relation; conformity; resemblance; connection; as, the affinity of sounds, of colors, or of languages.

3. (n.) Companionship; acquaintance.

4. (n.) That attraction which takes place, at an insensible distance, between the heterogeneous particles of bodies, and unites them to form chemical compounds; chemistry; chemical or elective affinity or attraction.

5. (n.) A relation between species or higher/ groups dependent on resemblance in the whole plan of structure, and indicating community of origin.

6. (n.) A superior spiritual relationship or attraction held to exist sometimes between persons, esp. persons of the opposite sex; also, the man or woman who exerts such psychical or spiritual attraction.