What does calcar mean?
Calcar is a specialized noun used chiefly in anatomy and botany to denote a spur — a pointed, spur-shaped projection on an organism. In zoology it most often refers to the bony or horny spur found on a bird's tarsus, as in gamecocks, where the structure may be used in combat; comparable projections occur on the limbs of certain other animals. In botanical usage, a calcar is a spur-like outgrowth of a floral organ, most famously the nectar-bearing hollow spur seen at the base of petals in orchids and violets. The word derives directly from Latin, in which calcar meant both a heel-spur worn for riding and, figuratively, anything that goads one onward. Because it belongs almost entirely to technical registers, calcar seldom appears in general writing, where the plain English word 'spur' carries the same sense. Its value lies in precision: biologists rely on it when describing morphology exactly, without ambiguity about which kind of projection is meant.
nounA spur-shaped projection or outgrowth, especially one on an animal's limb (such as a bird's tarsus) or a spur-like appendage on a plant part.
- A spur-shaped bony or horny projection on an animal's leg, especially a bird's tarsus.
- A spur-like outgrowth or hollow appendage on a plant structure such as a petal.
"The rooster's sharp calcar curved backward from its tarsal bone."
"Ornithologists noted the prominent calcar on each leg of the adult gamecock."
"In some orchid species, the calcar at the base of the lip stores nectar deep within its hollow tip."
The regular plural 'calcars' is standard in English-language biological texts; the Latin-style plural 'calcaria' occasionally appears in older systematic literature.
"Mature males typically develop larger calcars than females of the same species."
The same Latin root that gives us 'recalcitrant' — literally 'kicking back' — also names the actual spur a fighting rooster wears into battle.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of calcar
Calcar comes straight from Latin calcar, meaning a spur — both the rider's heel-spur and, by extension, any stimulus or goad. The Latin noun derives from calx, the heel, the same root that yields 'calcaneus' (the heel bone) and, through the related verb calcitrare ('to kick'), 'recalcitrant'. English borrowed the word in its anatomical and botanical senses, preserving the original Latin form essentially unchanged.
How calcar is actually used
A highly technical term confined mainly to anatomy, ornithology, and systematic botany; it is rarely encountered outside specialist literature. In everyday speech, 'spur' serves as the ordinary equivalent.
Easily confused with calcar
Calcareous means composed of or containing calcium carbonate (chalky or limy), whereas calcar denotes a spur-shaped anatomical or botanical projection.