multicellular organism (noun, pl. multicellular organisms) – organisms that are made of several cells that are clearly organized to communicate and function as a new entity. The boundary between unicellular and multicellular organisms is always obvious. All multicellular organisms show stages when they occur as a single cell. Many aggregates of single, even prokaryotic cells are highly organized with individual cells communicate and dividing separate functions between each other (e. g., the heterocytes of cyanobacteria). Thus, these single cells are not necessarily isolated, but they often act together like truly multicellular organism. Kind of:cell organization-type.