Illustrated Companion to the Latin Dictionary/Coemptio

This article incorporates text from a publication now in the public domain: Rich, Anthony (1849). The illustrated companion to the Latin dictionary, and Greek lexicon. p. vi. OCLC 894670115. https://archive.org/details/illustratedcompa00rich. 

COEMP'TIO. A marriage by civil contract, solemnized by a ficticious sale, at which the parties betrothed went through the ceremony of mutually selling themselves to one another, and supposed to have first come into use when intermarriages between the patrician and plebeian families became lawful, A. U. C. 308. Cic. Muret. 12. Non. Marc. s. v. Nubentes, p. 531.