noun a spur, or spurlike prominence.
2. calcar ·noun a hollow tube or spur at the base of a petal or corolla.
3. calcar ·noun a curved ridge in the floor of the leteral ventricle of the brain; the calcar avis, hippocampus minor, or ergot.
4. calcar ·noun a slender bony process from the ankle joint of bats, which helps to support the posterior part of the web, in flight.
5. calcar ·noun a kind of oven, or reverberatory furnace, used for the calcination of sand and potash, and converting them into frit.