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).
Cholesterol is a type of lipid (fat). Lipids are substances that do not dissolve in water but are soluble in organic solvents such as chloroform or dry cleaning fluids. Other important types of lipid include triglycerides and fatty acids. Lipids have several important roles in the body, providing: 1  a source and store of energy. 2  an important part of the membrane surrounding every body cell.