WordReference Random House Unabridged Dictionary of American English © 2026
the•ri•an
(thēr′ē ən),USA pronunciation adj.
n.
- Biology(in some classification systems) belonging or pertaining to the group Theria, comprising the marsupial and placental mammals and their extinct ancestors.
n.
- Mammalsa therian animal.
- Greek thēría, plural of thēríon wild beast) + -an
- Neo-Latin Theri(a) name of the group (