Meaning

noun scalelike structure between the base of the wing and the halter of a two-winged fly

noun tuft of small stiff feathers on the first digit of a bird's wing

originEtymology tree Proto-Indo-European *h₂eǵ-? Proto-Indo-European *-os Proto-Indo-European *h₂eḱs-der. Proto-Italic *aksis Latin axis Latin *axla Latin ala Proto-Indo-European *-lós Proto-Indo-European *-elós Proto-Italic *-elos Latin -ulus Latin -ulabor. English -ula English alula From Latin ala (“wing”) + English -ula.

Etymology from Wiktionary, CC BY-SA 3.0