(Ἀχλύς), according to some ancient cosmogonies, the eternal night, and the first created being which existed even before Chaos. According to Hesiod, she was the personification of misery and sadness, and as such she was represented on the shield of Heracles (Scut. Herc. 264, &c.): pale, emaciated, and weeping, with chattering teeth, swollen knees, long nails on her fingers, bloody cheeks, and her shoulders thickly covered with dust.
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890