group
[OED]: 2. gen. An assemblage of persons, animals, or material things, standing near together, so as to form a collective unity; a knot (of people), a cluster (of things). In early use the word often conveys a notion of confused aggregation, which in recent use is not implied.
Natural or anthropogenic clusters of objects, organisms or structural features. Migratory birds often form large flocks; fish form ‘schools’; trees may occur in pure ‘stands’. Grouping of organisms often depends on intra- and inter-specific communication and coordination. Visualizations of variables or properties may form natural groups, e.g. the halogens in the periodic table. Classification schemes (taxonomies) contain more or less inclusive groupings (taxons). The term population refers to one species (usually considered as interbreeding).
