calcar

noun

1. A small oven or furnace, used for the calcination of sand and potash, and converting them into frit.
2. A spur-like projection.

   “... a calcar, the apical spine of the inner series must in many of the species be also considered as such, since the appearance of both, and their position as regards the calcaria, are precisely similar. This apical spine of the inner[…]”

   “... The calcaria are frequently specified in the taxonomy of insects and are [...] a calcar is known as a strigilis. [...] A calcar and sometimes some of the adjacent setae are used for closing the[…]”

   “... calcars. When the tail is long (equal to or longer than the length of the hind legs) and calcars are present [...] calcar is absent in all known specimens[…]”