Interface and colloid science

Interface and Colloid Science deals with heterogeneous systems. "Fundamentals of Interface and Colloid Science by J.Lyklema ^[1] offer following definition of colloid:

"...an entity, having at least in one direction a dimension between 1 nanometer and 1 micrometer. The entities may be solid, or liquid, or, in some cases, even gaseous. They are dispersed in the medium..."