ultramicroscopic
'>c : a group of obviously related units of which the degree and nature of the relationship is imperfectly known
: the sum of factors (such as symptoms) characterizing a disease or condition //primary tuberculous complex
: a chemical association of two or more species (such as ions or molecules) joined usually by weak electrostatic bonds rather than covalent bonds
: a building or group of buildings housing related units //an apartment complex //a sports complex