adjective: (botany) Having male (staminate), female (pistillate), and bisexual flowers on the same plant (also known as "polygamous"), like Fraxinus excelsior
adjective: (botany) Belonging to the former Linnæan order Trioecia, consisting of plants of this type.
adjective: (zoology) Having three sexes: male, female and hermaphrodite, as some nematodes.
