Definition of SET THEORY. : a branch of mathematics or of symbolic logic that deals with the nature and relations of sets. â set theoretic adjective. See set theory defined for kids. ADVERTISEMENT.
Broadly, the term lipid is encompasses fats (including saturated, monoglyceride, diglyceride and triglyceride), waxes, sterols, phospholipids in the membranes of cells and fat soluble vitamins. Lipid is a basic term representing a molecule that is fat soluble (vs. water soluble).
Oil is a type of lipid known as a triglyceride. Solid triglycerides are called fats and liquid triglycerides are called oils. Credit: Thomas Vogel/E+/Getty Images.