the condition of open or closed polyamorous relationships consisting of primary, secondary and tertiary levels of interaction and interconnection
Paul and Jane are married and are each others' primary relationship. Jane has a secondary relationship with Karl, who would be Paul's tertiary relationship. These people are practicing polyamority.
PolyAmorists tend to focus more on the interpersonal and romantic connections with their partners, thus differentiating their practice from Swingers. Sexual activity does occur, just as it does in monogamous marriages.
Having a loving (usually sexual) relationship with more than one person at a time with the knowledge of all concerned.
Sue was in a polyamorus relationship where she had love making trysts with both Robert and Charles during the week and no one was angry, not even her husband William.