1. The total complex of biotic communities occupying and characterizing a particular geographic area or zone.
2. A biotic community of plants and animals; specifically, such a community in a prehistoric period.
3. A biogeographical region or formation; a major regional ecological community characterized by distinctive life forms and principal plant (terrestrial biomes) or animal (marine biomes) species.
4. A climatically controlled group of plants and animals of a characteristic composition and distributed over a wide area; such as, tropical rain forest, tundra, temperate grassland, desert, savanna, mountain habitats, taiga (a northern coniferous forest zone, especially in Siberia, adjacent to tundra), and other northern coniferous forests, etc.
5. A major regional community of plants and animals with similar life forms and environmental conditions.

It is the largest geographical biotic unit, group, or mass; and is named after the dominant type of vegetation; such as, tropical rain forest, grassland, or coral reef.

6. A complex biotic community existing in a given region, produced by the interaction of climatic factors, living organisms, and substrate.

A community that has developed to take advantage of existing vegetation; such as, tundra, coniferous forest, or grassland.