Spur on a bird's leg or wing

Wiktionary Word definitions in Wiktionary
Etymology 1 n. A small oven or furnace, used for the calcination of sand and potash, and converting them into frit. Etymology 2 n. (context botany anatomy English) A spur-like projection.

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Hippocampus \Hip`po*cam"pus\, n. [L., the sea horse, Gr. ? a hippocampus (in senses 1 and 2); "i`ppos horse + ? to bend.] (Class. Myth.) A fabulous monster, with the head and fore quarters of a horse joined to the tail of a dolphin or other fish ( Hippocampus ...

Wikipedia Word definitions in Wikipedia
The calcar , also known as the calcaneum , is the name given to a spur of cartilage arising from inner side of ankle and running along part of outer interfemoral membrane in bats , This is to help spread the interfemoral membrane, which is part of the wing ...