Definition for Sebum
From Biology Forums Dictionary
Sebaceous glands secrete the oily, waxy substance called sebum that is made of fat (lipids), wax, and the debris of dead fat-producing cells. In the glands, sebum is produced within specialized cells and is released as these cells burst; sebaceous glands are thus classified as holocrine glands. Seborrhoea is the name for the condition of greasy skin caused by excess sebum. Sebum is odorless, but its bacterial breakdown can produce odors. Sebum is the cause of some people's experiencing "oily" hair, as in hot weather or if not washed for several days. Earwax is partly composed of sebum.