διαύγεια

ἡ
2. translucency, Plu. 2.914b, Hierocl. CA 26p.480M.: metaph. of sayings, clarity, Plu. 2.408e.
II. hole to admit light, D.S. 17.82; peephole, Procl. Hyp. 3.25.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project