Final answer:
Oily substances in skincare are known as emollients, which are moisturizers that prevent water loss from the skin, and are found in oil-in-water or water-in-oil creams and ointments.
Step-by-step explanation:
Substances that are oily in nature are known as emollients. Emollients, such as petrolatum, cetyl alcohol, lanolin, and silicone oils, among others, are moisturizers that help hydrate the skin by creating a barrier that prevents water loss. They are found in various skincare products like lotions, creams, and ointments. Oil-in-water or water-in-oil creams are two types of emulsions used in these products. Ointments, a more oil-dominant form, are particularly effective emollients.