Crosswords Solver

Answer: dioptral
Answer	Crossword Clue
dioptral	pertaining to diopter (a measure of refractive power, also DIOPTRE)
dioptral	instrument, invented by Hipparchus, to measure the apparent diameter of the sun or moon or to estimate the size or elevation of distant objects
dioptral	unit of measure of the refractive power of a lens, having the dimension of the reciprocal of length and a unit equal to the reciprocal of one meter

Crossword

a puzzle consisting of a grid of squares and blanks into which words crossing vertically and horizontally are written according to clues.

Answer: dioptral