sagitta

Sagitta, sagittae, f., first declension. A plain concrete noun that carries almost no metaphorical freight in classical prose - it is the thing on the bowstring, nothing more. Poets are less restrained, firing Cupid's sagittae at anyone standing still, and the Psalms hand the same arrows to God.

The archer is a sagittarius, which covers both the auxiliary bowman in a Roman army and the constellation, and the adjective sagittarius sits behind the modern star sign unchanged. Italian saetta and Spanish saeta descend from the noun directly and both still mean an arrow or a bolt of lightning. English took only the technical sagittal, "arrow-shaped", used of the suture running front to back over the top of the skull.