Easton's Bible Dictionary: M. G. Easton, M.A., D.D.
To promise "by one's truth." Men and women were betrothed when they were engaged to be married. This usually took place a year or more before marriage. From the time of betrothal the woman was regarded as the lawful wife of the man to whom she was betrothed (Dt. 28:30; Judg. 14:2, 8; Mt. 1:18-21). The term is figuratively employed of the spiritual connection between God and his people (Hos. 2:19, 20).