Black's Law Dictionary (2nd edition)dictionaries

Coemptio

Mutual purchase, one of the modes in which marriage was contracted among the Romans. The man and the woman delivered to each other a small piece of mon-ey. The man asked the woman whether she would become to him a paterfamilias, (mis-tress of his family,) to which she replied that she would. In her turn she asked the man

Source: Black's Law Dictionary 2nd Ed (1910)