What is "spurious wing"

Spurious \Spu"ri*ous\ (sp[=u]"r[i^]*[u^]s), a. [L. spurius.]

1. Not proceeding from the true source, or from the source pretended; not genuine; counterfeit; false; adulterate.

2. Not legitimate; bastard; as, spurious issue. ``Her spurious firstborn.''
   --Milton.

   Spurious primary, or Spurious quill (Zo["o]l.), the first, or outer, primary quill when rudimentary or much reduced in size, as in certain singing birds.

   Spurious wing (Zo["o]l.), the bastard wing, or alula.

   Syn: Counterfeit; false; adulterate; supposititious; fictitious; bastard. [1913 Webster] -- Spu"ri*ous*ly, adv. -- Spu"ri*ous*ness, n.

n. tuft of small stiff feathers on the first digit of a bird's wing [syn: bastard wing, alula]