Definition of alula in US English:



  • technical term for bastard wing
    • ‘Yearlings in the study were identified in the hand by the olivegreen (rather than blue) edges of their alulae and primary coverts.’
    • ‘Although the alula is absent, the third finger probably had the same function in controlling separation of the upper surface airflow.’
    • ‘‘The alula is essential in modern birds for low-speed flight and maneuverability,’ they wrote.’
    • ‘It has pure white body feathers except for the black alulae, primary techrices and primary remiges.’
    • ‘He discovered the vortices that are produced off the wings, and observed the alulae, or ‘thumbs’ of the wings.’


Late 18th century: modern Latin, literally ‘small wing’, diminutive of ala.