Webster's Revised Unabridged Dictionary · 1913

Calcar

Calcar , noun

[Latin calcaria lime kiln, from calx, calcis, lime. See Calx.]

(Glass manuf.) A kind of oven, or reverberatory furnace, used for the calcination of sand and potash, and converting them into frit. — Ure

Calcar (#) , noun

[Latin, a spur, as worn on the heel, also the spur of a cock, from calx, calcis, the heel.]

1.
(Botany) A hollow tube or spur at the base of a petal or corolla.
2.
(Zoology) A slender bony process from the ankle joint of bats, which helps to support the posterior part of the web, in flight.
3.
(a) (Anatomy) A spur, or spurlike prominence.
(b)
(Anatomy) A curved ridge in the floor of the lateral ventricle of the brain; the calcar avis, hippocampus minor, or ergot.