What does alula mean?
The alula is a small but aerodynamically important structure on a bird's wing: a tuft of three to six feathers attached to the first digit — essentially the bird's thumb — that sits at the leading edge of the wing. By extending the alula, a bird opens a narrow slot between it and the main wing, which keeps airflow attached at high angles of attack and delays stalling during slow flight, takeoff, and landing. Because of this role, ornithologists sometimes call it the 'bastard wing.' The word derives from the Latin diminutive of ala, meaning wing, so it literally means 'little wing.' A second, unrelated sense appears in astronomy, where Alula Borealis and Alula Australis are two stars marking the far end of the Great Bear's tail in Ursa Major. Though technical rather than everyday vocabulary, the alula offers a vivid example of how anatomy and flight engineering meet in birds.
A group of small feathers on a bird's first digit, projecting from the leading edge of the wing and acting as a low-speed control surface; also called the bastard wing.
"The owl adjusted its alula to keep lift steady as it glided in for a silent landing."
Used mainly in ornithology and technical writing about bird flight.
Either of two stars, Alula Borealis and Alula Australis, at the northernmost end of the constellation Ursa Major.
"Alula Australis is notable as one of the first binary stars whose orbit was calculated."
Always capitalized in this astronomical sense.
The plural follows the Latin first-declension pattern and is standard in ornithological writing when referring to both wings of a bird.
"Both alulae were fully spread as the heron braked above the water."
Birds have thumbs — and the tiny tuft of feathers on them, the alula, is what lets a hummingbird hover and an eagle land without stalling.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of alula
The word alula comes from Latin, where it is the diminutive of ala, meaning 'wing' or 'armpit' — literally a 'little wing.' It was adopted into scientific English nomenclature for the feathered first digit of a bird's wing. Related words sharing the root include alar (relating to wings) and alate (winged), both likewise drawn from Latin ala. The astronomical sense arose independently through Arabic star naming traditions, in which the stars at the tip of Ursa Major's tail were associated with the 'first leap' of the gazelle, later rendered in Latin as alula.
Related word forms
How alula is actually used
Primarily a technical term used in ornithology, aviation-inspired writing about birds, and astronomy; rare in everyday conversation. In ornithological literature it is often called the 'bastard wing,' a somewhat dated but still common alternative name.
Easily confused with alula
Ala is the Latin word for a wing or winglike structure generally, while alula is its diminutive referring specifically to the small feathered 'thumb' on a bird's wing.