Sagitta

·noun The keystone of an Arch.

II. Sagitta ·noun A small constellation north of Aquila; the Arrow.

III. Sagitta ·noun The larger of the two otoliths, or ear bones, found in most fishes.

IV. Sagitta ·noun A genus of transparent, free-swimming marine worms having lateral and caudal fins, and capable of swimming rapidly. It is the type of the class Chaetognatha.

V. Sagitta ·noun 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.