Lewis & Short

oesypum, i, n., = οἴσυπος, the greasy sweat and dirt of unwashed wool, Plin. 29, 2, 10, § 35; cf. id. 29, 6, 36, § 112; 30, 4, 10, § 28.
Used as a cosmetic by the Roman ladies, Ov. A. A. 3, 213; id. R. Am. 354.