concubinage 的詞源

14世紀晚期，“做妾的狀態； 在沒有合法婚姻的情況下共同居住的行爲或實踐”，源自古法語 concubinage，來自 concubin，源自拉丁語 concubina（見 concubine）。在古羅馬法律中，“是指在婚姻沒有法律障礙的人之間的永久同居。”

It was distinguished from marriage proper (matrimonium) by the absence of "marital affection"—that is, the intention of founding a family. As no forms were prescribed in the later times either for legal marriage or concubinage, the question whether the parties intended to enter into the former or into the latter relation was often one of fact to be determined from the surrounding circumstances, and especially with reference to a greater or less difference of rank between them. [Century Dictionary]

它與正式婚姻（matrimonium）的區別在於缺乏“婚姻感情”——即建立家庭的意圖。由於在後期既沒有規定法律婚姻的形式，也沒有規定做妾的形式，因此，當事人是否打算進入前者或後者的關係，常常是一個事實問題，需要根據周圍的情況，特別是他們之間的地位差異的大小來確定。[世紀詞典]