Lewis & Short

smegma (smigma and zmeg-ma), ătis (dat. plur. smegmatis, Plin. 31, 7, 42, § 92), n., = σμῆγμα, a cleansing medicine, a detergent, Plin. 22, 25, 74, § 156; 34, 13, 36, § 134.
For making the skin smooth, Plin. 24, 7, 28, § 43; cf. Becker, Gallus, 3, p. 64 (2d edit.): afferte mihi smigmata, Vulg. Dan. 13, 17.