From the ancient Greek urá 'tail' and stýlos 'stick'.

Urostyle - fused into a stick-shaped ossicle of the bodies of the last vertebrae of bony fishes, directed into the upper lobe of the caudal fin.

In bony fishes, the urostyle is formed by the fusion of only the last caudal vertebrae (e.g., Sander lucioperca). It is adjacent to the posterior caudal vertebrae of the fish, bent upward and together with the hypuralia performs the function of supporting the leathery rays of the caudal fin.