Longman Dictionary of Contemporary English
Wiktionary
n. A marital relationship in which each partner agrees that the other partner may have sexual relations with other people as he or she sees fit.
WordNet
n. a marriage in which each partner is free to enter into extraneous sexual relationships without guilt or jealousy from the other
Wikipedia
Open marriage typically refers to a marriage in which the partners agree that each may engage in extramarital sexual relationships, without this being regarded as infidelity. There are many different styles of open marriage (such as swinging and polyamory), each with the partners having varying levels of input on their spouse's activities.
Open Marriage was a best selling book published by M. Evans & Company in 1972 by Nena O'Neill and George O'Neill. It was on the New York Times best-seller list for 40 weeks. It has been translated into 14 languages and has sold more than 35 million copies worldwide according to the publisher.
The book redefined the meaning of the term " open marriage" and helped foster a sexual revolution in the 1970s. The O'Neills conceived open marriage as one in which each partner has room for personal growth and can develop outside friendships. Most chapters in the book dealt with non-controversial approaches to revitalizing marriage in areas of trust, role flexibility, communication, identity, and equality. The authors intended "to strip marriage of its antiquated ideals and romantic tinsel and find ways to make it truly contemporary."
However, chapter 16, entitled "Love Without Jealousy", devoted 20 pages to the proposition that an open marriage could include some forms of sexuality with other partners. These concepts entered the cultural consciousness and the term "open marriage" became a synonym for sexually non-monogamous marriage, much to the regret of the O'Neills. In the 1977 publication of The Marriage Premise, Nena O'Neill advocated sexual fidelity in the chapter of that name. By then however, the concept of open marriage as sexually non-monogamous marriage had gained a life of its own.
The marital suggestions in the book were largely conventional, even at the time. The New York Times writes that some of its "bolder suggestions [now] seem not so much daring as painfully naïve." The book stressed that women should lead meaningful lives, in alignment with feminist ideas.
Usage examples of "open marriage".
In private, they had an open marriage, as Perry and Diana do in this novel, once Perry's jealousy is cured.
It's about expanding marriage to include polygamy, polyamory, transsexual marriages, and open marriage.
Blue knew himself to be by far the most popular Citizen of Proton, be -- cause of his steadfast efforts to mitigate the lot of serfs and his open marriage to a machine.
Blue knew himself to be by far the most popular Citizen of Proton, because of his steadfast efforts to mitigate the lot of serfs and his open marriage to a machine.