i.e. Thy step-mother. Examples of this are Genesis 35:22, Genesis 49:4 1 Corinthians 5:1. It is thy father's nakedness, by interest and relation; that which he only may uncover.
Related Commentaries of Leviticus 18:8
Leviticus 18:8
8 The nakedness of thy father's wife shalt thou not uncover: it is thy father's nakedness.