They have turned their backs on monogamy and rejected traditional mores in their love lives - and now a group of "polyamorous'' lovers have decided they need a new set of words to describe their lifestyle.
Polyamorous people live in open relationships where they may have several partners of either sex who are also in other relationships.
The movement began in California in the 1990s but has burgeoned in recent years, thanks, in part, to the internet and the publication of studies describing the phenomenon.
They see themselves as returning to a more natural state of living, where people do not have secret affairs behind their partners' backs and reject what they see as an artificial Western insistence on fidelity for life with one partner.
The polyamorous community's so-called bible is a 1997 book called The Ethical Slut that describes living with and loving multiple partners. The American author of the book urged women to reclaim the word slut as a positive term to describe the possibility of having simultaneous relationships with a number of people.
Since then internet chat rooms, mailing lists and other sites focusing on polyamory have sprung up across the world, particularly in the US and UK. A UK mailing list currently has more than 200 members, and Britain's first conference on the subject - called the "Poly-Day'' - was held last November.
Meg Barker, a psychologist who also lives a polyamorous lifestyle, has researched the issue. She presented a paper at the British Psychological Society Conference in Manchester last week, at which she described how the movement was evolving an entirely new dictionary of words to describe the way in which its followers lived.
"The problem is that in Western culture a lot of the words we have to describe emotions are based on the concept of monogamous relationships.
"We have words like jealousy, which in polyamorous relationships you don't really get, but there is not a word to describe the warm feeling that a polyamorous person will get when they see one of their partners getting on with another of their partners.
"It is kind of the opposite of jealousy. A lot of importance is placed on being able to describe the emotions that we have and this is why the poly community has started to come up with its own words which are now rapidly being adopted."
The polyamorous community in America has evolved its own lexicon, but British adherents are now coming up with their own words, Ms Barker said.
These include "frubble'' - to describe the feeling of warmth and happiness when seeing one of your partners getting on well with either one of your partners or one of their lovers.
Ms Barker said: "Some cultures, for instance, traditional Hawaiian cultures, have always had words like this because they have practised polygamy and have always been used to the idea.
"A lot of our words have been started on internet discussion sites where people have been frustrated that they can't express themselves and the way the live." She added: "Some people can be very judgemental but when you look at the figures of the number of people who have affairs and who are desperately unhappy in monogamous relationships it seems a bit strange."
She estimates that at least 2,000 people in Britain may be living polyamorous lifestyles, although many may be reluctant to admit it.
'Of course, I do get jealous, but it passes'
Meg Barker, 30, from south London, has been in polyamorous relationships for three years.
She lives part of the week with her girlfriend, Annie, and the rest with her boyfriend, Erich, and has two other lovers - a man and a woman.
Her partners also have other partners, and Ms Barker's sister lives a similar lifestyle.
Ms Barker, an academic, said: "I always knew I was capable of loving a lot of different people at the same time, but when I was growing up it was difficult to know how I could follow that kind of life."
She says the main problem is finding time to spend with all her lovers. "You have to be pretty organised and sometimes it can be difficult to see everyone you want, but all of my partners get on well and we have times when we all meet up."
Her parents, she says, are supportive, although she says other people can be judgemental.
"Some people, especially men, assume I am more open to offers...Some polyamorous people do have a lot of casual sex but for me it is about having loving relationships with a number of people at the same time.
"Of course, I do get jealous sometimes, especially when one of my partners has started a new relationship and you can see they are very excited about it, but [it] quickly passes when I realise they are not going to replace me in my partner's affections."
THE LEXICON OF (MULTIPLE) LOVE
*Frubble Describes the feeling of warmth and happiness when seeing one of your partners getting on well with one of your partners or one of their lovers
*Wibble The temporary feeling of insecurity when seeing a partner being loving or close with another of their partners
*Metamour Used to describe your relationship with one of your partner's partners
*NRE Short for "new relationship energy'' - a phrase describing how one partner behaves when starting a new relationship with a new lover
*Polyamory Loving more than one person
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