Found 1 items, similar to dioptra.
English → English (gcide) Definition: Dioptra Diopter \Di*op"ter\, ||Dioptra \Di*op"tra\, n. [L. dioptra, fr. Gr. ?. See 2d Dioptric.] An optical instrument, invented by Hipparchus, for taking altitudes, leveling, etc. [1913 Webster] ||