An Etymological Dictionary of Astronomy and Astrophysics

The reflection of light waves in which the reflected waves travel in a definite direction, and the directions of the incident and reflected waves make equal angles with a line perpendicular to the reflecting surface. Same as → regular reflection; opposite of → diffuse reflection.

Etymology (EN): From L. specularis, from speculum “mirror;”
→ reflection.

Etymology (PE): Bâztâb, → reflection; âyenevâr “mirror-like,” from âyené, → mirror + -vâr similarity suffix.