Unicorn
A unicorn refers to a single person who is willing to join a couple for intimate encounters and/or long-term dating.
The term “unicorn” comes from the idea that such a person is rare and elusive, just like a mythical unicorn.
In Heterosexual Spaces
The term is commonly used in the swinging and polyamorous communities, where couples may seek out a unicorn to enhance their sexual experiences or explore new aspects of their sexuality together.
In LGBTQ Spaces
Unicorns exist in the LGBTQ community, but they're simply called "unicorns".
Related Terms
Some communities decide to segregate unicorns by sex/gender. In these cases, "unicorn" refers exclusively to female unicorns, while male unicorns will be referred to as a "dragon" (if they expect submission from the couple) or a "centaur" (if they are bisexual).
Additional reading
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