Mosiah 11:2. Concubines and Whoredoms

From Book of Mormon Student Manual, p. 74:

Concubines in the Old Testament “were considered to be secondary wives, that is, wives who
did not have the same standing in the caste system then prevailing as did those wives who were not called concubines” (Bruce R. McConkie, Mormon Doctrine, p. 154). Concubines had full protection as wives and did not violate the law of chastity when the marriages were approved by the Lord (see D&C 132:34–43). In the time of King Noah, however, the word concubine referred to the wicked practice of a man living with more than one woman, in or out of marriage, without God’s approval.
The word whoredoms refers to any perversion of the laws of chastity and virtue.