Who in the world would want to know the definition of concubine? That would be me. Why? Two reasons. One: I am a genealogist and I've recently come across the word in the ancestry message boards. Two: I write historical novels.
I looked up the word concubine and this is what I've found:
Concubinage [F] The cohabiting of a man and a woman who are not legally married; state of being a concubine. Concubinage is recognized in many systems of primitive law, as that of the ancient Hebrews.
Concubine - fr. con - cubare to lie down. A woman who cohabits with a man without being his wife; a kept mistress.
concupiscence - ardent desire; hence sexual lust.
concupiscent - lustful. [Latin, derived of con - cupere to desire.]
concupiscible (a rare word these days) That is most desirable; also lustful.
Suellen Ocean is the author of the historic novels The Lies of the Lion and The Guild available at Ocean-Hose. Find it here: http://www.pacificsites.com/~oceanhose/