Syneisaktism
Syneisaktism, also spelled "syneisactism" (from Ancient Greek συνείσακτος , suneísaktos, “(adjective) introduced together; (noun) participant in syneisaktism”, from συνεισάγω, suneiságō, “to bring in together”, from συν-, sun-, “together” + εἰσάγω, eiságō, “to bring in, introduce), is the practice of "spiritual marriage", which is where a man and a woman who have both taken vows of chastity live together in a chaste and non-legalized partnership. More often than not, the woman would move into the house of the man, and they would live as brother and sister, both committed to the continuation of their vows of chastity.