What is cosmetic? What is cosmetic? A preparation, such as powder or a skin cream, designed to beautify the body by direct application.Something superficial that is used to cover a deficiency or defect.Serving to beautify the body, especially the face and hair.Serving to modify or improve the appearance of a physical feature, defect, or irregularity: cosmetic surgery. Decorative rather than functional: cosmetic fenders on cars. Lacking depth or significance; superficial: made a few cosmetic changes when she took over the company.