sagitta

The keystone of an arch.

The distance from a point in a curve to the chord; also, the versed sine of an arc; so called from its resemblance to an arrow resting on the bow and string.

The larger of the two otoliths, or earbones, found in most fishes.

Any arrowworm, of the genus Sagitta.

A small autumn constellation of the northern sky, said to resemble an arrow. It lies between the constellations of Vulpecula and Aquila.