A micelle or micella is an aggregate of surfactant amphipathic lipid molecules dispersed in a liquid, forming a colloidal suspension. A typical micelle in water forms an aggregate with the hydrophilic "head" regions in contact with surrounding solvent, sequestering the hydrophobic single-tail regions in the micelle centre.

In chemistry, a supramolecular assembly is a structure consisting of molecules held together by noncovalent bonds. While a supramolecular assembly can be simply composed of two molecules, or a defined number of stoichiometrically interacting molecules within a quaternary complex, it is more often used to denote larger complexes composed of indefinite numbers of molecules that form sphere-, rod-, or sheet-like species. Colloids, liquid crystals, biomolecular condensates, micelles, liposomes and biological membranes are examples of supramolecular assemblies, and their realm of study is known as supramolecular chemistry. The dimensions of supramolecular assemblies can range from nanometers to micrometers. Thus they allow access to nanoscale objects using a bottom-up approach in far fewer steps than a single molecule of similar dimensions.