Affinity

Boyd’s Bible Dictionary:

Relation by marriage and not by blood or birth (1 Kings 3:1¹And Solomon made affinity with Pharaoh king of Egypt, and took Pharaoh's daughter, and brought her into the city of David, until he had made an end of building his own house, and the house of the Lord, and the wall of Jerusalem round about. (1 Kings 3:1)). For preventive degrees see Leviticus 18:6-17⁶None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the Lord. ⁷The nakedness of thy father, or the nakedness of thy mother, shalt thou not uncover: she is thy mother; thou shalt not uncover her nakedness. ⁸The nakedness of thy father's wife shalt thou not uncover: it is thy father's nakedness. ⁹The nakedness of thy sister, the daughter of thy father, or daughter of thy mother, whether she be born at home, or born abroad, even their nakedness thou shalt not uncover. ¹⁰The nakedness of thy son's daughter, or of thy daughter's daughter, even their nakedness thou shalt not uncover: for theirs is thine own nakedness. ¹¹The nakedness of thy father's wife's daughter, begotten of thy father, she is thy sister, thou shalt not uncover her nakedness. ¹²Thou shalt not uncover the nakedness of thy father's sister: she is thy father's near kinswoman. ¹³Thou shalt not uncover the nakedness of thy mother's sister: for she is thy mother's near kinswoman. ¹⁴Thou shalt not uncover the nakedness of thy father's brother, thou shalt not approach to his wife: she is thine aunt. ¹⁵Thou shalt not uncover the nakedness of thy daughter in law: she is thy son's wife; thou shalt not uncover her nakedness. ¹⁶Thou shalt not uncover the nakedness of thy brother's wife: it is thy brother's nakedness. ¹⁷Thou shalt not uncover the nakedness of a woman and her daughter, neither shalt thou take her son's daughter, or her daughter's daughter, to uncover her nakedness; for they are her near kinswomen: it is wickedness. (Leviticus 18:6‑17), and MARRIAGE.

Concise Bible Dictionary:

In relationship by marriage, the principal point of interest is the degrees of relationship within which marriage was forbidden. Thus a woman must not marry two brothers, unless her husband had died without issue, when the brother was required to raise up seed to the deceased. Apparently a man might by the law of Moses marry his deceased wife’s sister; but not the second in the lifetime of the first(Lev. 18:18¹⁸Neither shalt thou take a wife to her sister, to vex her, to uncover her nakedness, beside the other in her life time. (Leviticus 18:18)), though Jacob before the Law was given had two sisters for wives at the same time. Near relatives may not marry (Lev. 18). Many codes respecting the degrees of affinity have been made by nations, more or less in agreement with the law of Moses. See MARRIAGE.