From Latin sagitta (“arrow”).
sagitta (plural sagittas)
- The keystone of an arch.
- (geometry) 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.
- (anatomy) The larger of the two otoliths, or ear bones, found in most fishes.
Part or all of this entry has been imported from the 1913 edition of Webster’s Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
Unknown etymology. Probably from a pre-Latin Mediterranean language. 
Related terms 
See also 
- arcus m