Definition of bastard wing in English:

bastard wing

noun

  • A group of small quill feathers on the first digit of a bird's wing.

    • ‘About the size of a goldfinch, the bird sports a tuft of feathers technically known as an alula, or bastard wing, that would have helped it stay aloft at slow speeds.’
    • ‘The alula feather, also called the bastard wing, can be seen at the top center of the photo.’
    • ‘At the same time, he made an anatomical study of bird wings, demonstrating that the bastard wing acts as a brake.’
    • ‘Both young green and night herons elevate the bastard wing at times as they climb about the trees, but I have never seen them attempt to use it for grasping.’
    • ‘The bastard wing of birds is a rudimentary digit; and I believe that if fossil birds are found very low down in the series, they will be seen to have a double or bifurcated wing.’