Well derm is another term used for dermis which, in anatomy, is the thick layer of tissue below the epidermis that forms the true skin, containing blood capillaries, nerve endings, sweat glands, and hair follicles.
The definition of logy is: slow in movement or thought, or in other words sluggish.
The best definition that I can give for these two words is slow acting skin?
Another thought that comes to mind is the word dermatology which is the branch of medicine that studies the diagnosis and treatment of skin disorders.