Extended Strong's Greek Lexicon (Abbott-Smith based)
brightness
Usage: φέγγος, -ους, τό [in LXX chiefly for נֹגַהּ ;] light, brightness, usually with genitive of something that shines or reflects: of the moon, Mat.24:29, Mrk.13:24; of a lamp, Luk.11:33 (WH, RV, φῶς).† SYN.: αὐγή, q.v (AS)