Polyamory
Polyamory is the practice of being in a romantic or sexual relationship with more than one partner at once. People who are polyamorous may be in an open relationship (where everyone involved can have romance and sex with whoever they want) or may be in a closed group where the partners are expected to be romantic and sexual only with each other. Being in a closed polyamorous group is also known as polyfidelity. The word polyamory can be used as an umbrella term for relationships that are not monogamous, have multiple partners, or are non-exclusive.