LAT

Lewis Short

dĭoptra (noun F) = δίοπτρα:
* An optical instrument to measure the height of places, Vitr. 8, 6; for measuring the sun's shadow,Plin. 2, 69, 69, § 176.
Charlton T. Lewis, Charles Short, A Latin Dictionary

TLL

s. TLL
Thesaurus Linguae Latinae
memory