- In human sexuality, bisexuality describes people who are sexually and/or romantically attracted to both males and females.
- In botany, a bisexual flower is one that possesses both male (pollen-producing) and female (seed-producing) parts. Botanists call these flowers perfect or hermaphroditic. Species that possess separately sexed (unisexual) flowers, but have both types on the same indiviudual plant are called monoecious.
- Many non-human animal species also exhibit bisexual behavior. This is particularly common in hermaphroditic animals, but is also known in many other species such as the bonobo monkey. Bisexuality has been observed in over 500 species.