in Astronomy, the Arrow, a constellation of the northern hemisphere near the Eagle, and one of the 48 old asterisms. According to the fabulous ideas of the Greeks, this constellation owes its origin to one of the arrows of Hercules, with which he killed the eagle or vulture that gnawed the liver of Prometheus. In the catalogues of Ptolemy, Tycho, and Helvelius, the stars of this constellation are only five in number, while Flamstead made them amount to 18.

in Geometry, a term used by some writers for the absciss of a curve.

in Trigonometry, the same as the versed sine of an arch; being so denominated because it is like a dart or arrow, standing on the chord of the arch.