What does astragalus mean?
Astragalus is a noun with two well-established meanings. Most prominently, it is the botanical name of one of the largest genera of flowering plants, a member of the legume family encompassing thousands of species found across temperate regions of the Northern Hemisphere. Many of these herbs are known colloquially as milkvetches, while some North American species, called locoweeds, are notorious for poisoning grazing livestock. Certain species, particularly Astragalus membranaceus, have long histories in traditional Chinese medicine and are marketed today as dietary supplements under the name astragalus root. Separately, in anatomy, an astragalus is the ankle bone — the tarsal bone that receives the weight of the body from the tibia and fibula and transmits it to the foot, a sense shared with the term talus. Both meanings trace back to the Greek word for a knucklebone, reflecting the shape of the seed pods and the bone alike. The register is formal and technical: the word belongs chiefly to botany, medicine, and traditional-medicine marketing rather than everyday conversation.
A large genus of herbaceous flowering plants in the legume family Fabaceae, widely distributed across temperate regions; certain species are used medicinally and others are toxic to livestock.
"Astragalus includes well over two thousand species, ranging from alpine milkvetches to desert locoweeds."
Always capitalised and italicised when used as a formal genus name.
The talus, or ankle bone: the second-largest tarsal bone, which articulates above with the tibia and fibula and below with the calcaneus.
"An untreated fracture of the astragalus can impair blood supply to the bone and lead to avascular necrosis."
Modern anatomical usage increasingly prefers the term 'talus'; 'astragalus' persists especially in veterinary anatomy and older clinical literature.
For anatomical contexts the Latin plural astragali is standard, though the anglicised plural astragaluses is acceptable in informal use; for the plant genus, plural references usually say 'species of Astragalus' rather than pluralising the name.
"The excavation yielded a cache of sheep astragali, evidently used by the settlement's inhabitants as gaming pieces."
Ancient Greeks rolled sheep's ankle bones — actual astragali — as dice, making this one of the world's oldest gaming pieces long before it became a herbal supplement.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of astragalus
English borrowed astragalus directly from Latin, which took it from Greek astragalos, meaning the ankle joint or knucklebone; the Greeks used these bones as dice and counters, and the word entered English around the early seventeenth century chiefly in that anatomical sense. When Carl Linnaeus formalised botanical nomenclature in the eighteenth century, he applied the name to the large legume genus, reportedly because the shape of its pods or seeds recalled a knucklebone. The architectural term astragal descends from the same classical source, named for its resemblance to a rounded bone.
Related word forms
How astragalus is actually used
In botanical writing the genus name is always capitalised and italicised (Astragalus), following binomial nomenclature conventions; in general prose it appears lowercase. In medical contexts the word refers strictly to the ankle bone and is largely interchangeable with 'talus', which is now the preferred term among most anatomists. The architectural sense survives mainly in the shortened form 'astragal'.
Easily confused with astragalus
Asparagus is an edible vegetable shoot, while astragalus is a genus of mostly inedible leguminous herbs; the two share a similar rhythm and ending but nothing else.
An astragal is the narrow, rounded architectural moulding whose name derives from astragalus, whereas astragalus denotes either the plant genus or the ankle bone.