Concubinage is an interpersonal relationship in which a person engages in an ongoing sexual relationship with another person to whom they are not or cannot be married to the full extent of the local meaning of marriage. The inability to marry may be due to multiple factors such as differences in social rank status, an existing marriage, religious prohibitions, professional ones (for example Roman soldiers) or a lack of recognition by appropriate authorities. The woman in such a relationship is referred to as a concubine.