SAGITTA

noun the keystone of an arch.

2. sagitta ·noun a small constellation north of aquila; the arrow.

3. sagitta ·noun the larger of the two otoliths, or ear bones, found in most fishes.

4. 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.

5. 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.