Why is the ninth month called September?
"shaped like or resembling an arrow," 1540s, from Modern Latin sagittalis, from Latin sagitta "arrow" (see Sagittarius).
sagittal sag·it·tal (sāj'ĭ-tl)adj.
Of or relating to the suture uniting the two parietal bones of the skull.
Of or relating to the sagittal plane.