Suspension, a mixture of small particles and a liquid or gas. Suspensions differ from colloids and solutions mainly in the size of the particles in the mixture. Particles in a suspension are often large enough to be seen without magnification, and in many instances will eventually settle to the bottom. In a colloid, the particles are of microscopic size and ordinarily do not settle out. Smallest of all are the molecular- and atomic-sized particles present in solutions. Certain medicines, paints, and other products are prepared as suspensions. Muddy or silty water is a natural suspension.