alula vs bastard wing

alula and bastard wing both are nouns.

Word	Noun	Adjective	Verb	Adverb
alula	Yes	No	No	No
bastard wing	Yes	No	No	No

As nouns, alula and bastard wing are synonyms defined as:

alula and bastard wing: tuft of small stiff feathers on the first digit of a bird's wing

Other synonyms of alula include spurious wing.

alula (noun)	bastard wing (noun)
tuft of small stiff feathers on the first digit of a bird's wing	tuft of small stiff feathers on the first digit of a bird's wing
scalelike structure between the base of the wing and the halter of a two-winged fly