Looking for a smegma definition? Smegma is a white, greasy substance that builds up under the foreskin of an uncircumcised penis (and sometimes underneath the clitoral hood, the skin flap that covers the clitoris). It helps provide lubrication so the foreskin can slide smoothly against the glans (the head of the penis).
Definition. Smegma is made up of dead cells produced by smegma-forming prominences, small bumps on the inner layer of the foreskin. Gradually, new cells move to the surface and degenerate into an oily substance. Sebum, the oil we secrete from our skin, may also play a role in smegma formation. Smegma in women is a combination of dead skin cells and sebum, an oily substances secreted from the skin.
Function. When a man has an erection, the foreskin retracts, revealing the glans. Smegma lubricates the foreskin, helping it slide easily. Without smegma, friction would make the skin of the foreskin and glans rub together roughly.
After Circumcision. Even men who are circumcised--that is, who have had their foreskins removed--may produce smegma. This is because circumcision rarely removes all of the foreskin; there is usually a small piece left behind.
Misconceptions. Ever since the fear of masturbation took hold in the nineteenth-century (masturbation will make you go blind and so on), smegma has been thought unclean and blamed for disease. Several studies on mice in the mid-twentieth century even suggested that smegma causes cancer. More recent studies, however, have provided this link false. Smegma is just a natural part of our sexual function.
Considerations. Smegma can develop a strong smell and taste. This is especially a problem for uncircumcised men who have never learned how to properly clean their genitals, due perhaps to parental or societal embarrassment. Sexual hygiene is very important, so remember to wash your genitals (and under the foreskin) with soap and water.