Definition of pygostyle in English:

pygostyle

noun

Ornithology
  • (in a bird) a triangular plate formed of the fused caudal vertebrae, typically supporting the tail feathers.

    • ‘All birds, both fossil and modern, have reduced the tail to a mass of fused vertebrae termed the pygostyle.’
    • ‘The tail is shortened and fused to form a pygostyle which bears tail feathers (retrices).’

Origin

Late 19th century: from Greek pugē rump + stulos column.

Pronunciation:

pygostyle

/ˈpīɡəˌstīl/