包皮垢
Smegma \Smeg"ma\, n. [NL., fr. Gr. ???? soap, fr. ????? to wash off.] (Physiol.) The matter secreted by any of the sebaceous glands. Specifically: (a) The soapy substance covering the skin of newborn infants. (b) The cheesy, sebaceous matter which collects between the glans penis and the foreskin.
smegma n : a white secretion of the sebaceous glands of the foreskin