Erusin is the Hebrew term for betrothal. In modern Hebrew, "erusin" means engagement, but this is not the historical meaning of the term, which is the first part of marriage.

An engagement or betrothal is the period of time between the declaration of acceptance of a marriage proposal and the marriage itself. During this period, a couple is said to be fiancés, betrothed, intended, affianced, engaged to be married, or simply engaged. Future brides and grooms may be called fiancée (feminine) or fiancé (masculine), the betrothed, a wife-to-be or husband-to-be, respectively. The duration of the courtship varies vastly, and is largely dependent on cultural norms or upon the agreement of the parties involved.