calcar

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A spur or spurlike projection, such as one found on the base of a petal or on the wing or leg of a bird.
2. n. A furnace formerly used in glassmaking for calcination of materials into frit.

Century Dictionary and Cyclopedia

1. n. In botany, a spur; a hollow projection from the base of a petal or sepal; the nectary (nectarium) of Linnæus.
2. n. In anatomy, a projection into the posterior horn of the lateral ventricle of the brain of man and some other mammals; the calcar avis or hippocampus minor.
3. n. In ornithology, a spur. The horny process, with a bony core, borne upon the lower and inner part of the shank of sundry gallinaceous birds, as the turkey, pheasant, domestic cock, etc. It is of the same nature as a claw, or as the horns of cattle, but differs from a claw in being an offset from the side of a bone, not at the end of a phalanx. There is sometimes a pair of spurs, one above the other, on each shank, as in the genus Polyplectron. (See cut under calcarate.) Spurs are commonly developed only in the male sex, not passing a rudimentary condition, if found at all, in the female. (See cut under tarsometatarsus.)
4. n. In Rotifera, a spur-like setigerous process more or less closely attached to the single ganglion of these animals, near the trochal disk.
5. n. In Chiroptera, a slender elongated bone or cartilage upon the inner side of the ankle-joint, assisting in the support of the patagium.
6. n. [capitalized] [NL.] In entomology, a genus of atracheliate beetles, of the family Tenebrionidæ.
7. n. [capitalized] [NL.] In conchology, a genus of mollusks.
8. n. The spur forming part of any ceremonial costume.
9. n. In glass-works, an oven or furnace for calcining the materials of frit, prior to melting. Also called fritting-furnace.
10. n. In metallurgy, an annealing-arch or -oven.
11. n. In entomology, one of the spines at the tips of the tibiæ of certain insects, especially the Hymenoptera. Also called spur.

Wiktionary

1. n. A small oven or furnace
2. n. A spur-like projecction

GNU Webster's 1913

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