LSJ
α, ον, = Lat. asper, Ael. NA 1.26. ἄ. γράμματα invisible writing, Cat.Cod.Astr. 1.108 (the signf.
white is very late); ἄσπρον, τό, white of an egg, [Gal.] 14.560. name of an ingredient of incense, Aët. 16.146, 148.
Liddell-Scott-Jones, Greek-English Lexicon (9th ed., 1940)