What does uropygium mean?
Uropygium is a specialized anatomical noun used chiefly in ornithology for the terminal part of a bird's vertebral column. It encompasses the pygostyle, the compact terminal bone structure that provides a firm attachment for the tail feathers, together with the adjoining caudal vertebrae. The word therefore names a structural support rather than the feathers themselves or the whole tail. In descriptions of living birds and museum specimens, the uropygium may be discussed when identifying the shape, articulation, or development of this tail base. “Uropygial” is the familiar adjective, seen in terms such as “uropygial gland” and “uropygial coverts.” Because the term is highly specialized and uncommon in general prose, its plural uropygia appears chiefly in zoological and anatomical writing. Despite its specialized appearance, the word rewards attention with a vivid structural connection: it is the small bony platform from which a bird's tail fan takes flight.
nounThe terminal part of a bird's vertebral column, including the pygostyle and associated caudal vertebrae. It provides the bony support to which the tail feathers are attached.
- In ornithology, the terminal portion of a bird's vertebral column, comprising the pygostyle and associated caudal vertebrae and supporting the tail feathers.
"The uropygium supports the bird's long, fan-shaped tail."
"The field guide identifies the shape and articulation of the uropygium in the specimen."
"In adult birds, the uropygium supports the principal tail feathers."
The standard plural is used when referring to the terminal vertebral structures of multiple birds or to multiple examples described in zoological writing.
"The study compared the uropygia of several species of cranes."
A bird's spectacular tail fan depends on the uropygium—a compact bony platform that anchors its flight feathers.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does uropygium come from?
Uropygium was formed in New Latin from the Greek oura, meaning “tail,” and pygē, meaning “rump.” The compound was adopted in anatomical and ornithological usage to refer to the terminal vertebral structure supporting a bird's tail. Related English terms include pygidium and pygidial, from the same Greek root for the rump or posterior body region, and uropod, which shares the Greek element for “tail.”
Related word forms
How uropygium is actually used
A highly technical term used chiefly in ornithology, zoology, and comparative anatomy. It is uncommon in general prose, while the related adjective “uropygial” is more widely encountered.
Easily confused with uropygium
A pygidium is the terminal abdominal segment of many arthropods, whereas the uropygium is the terminal part of a bird's vertebral column.