Word of the Day Photography: Casey Horner bi·ome /ˈbīˌōm/ Learn to pronounce noun ECOLOGY plural noun: biomes a large naturally occurring community of flora and fauna occupying a major habitat, e.g. forest or tundra. A biome is a large region of Earth that has a certain climate and certain types of living things. Major biomes include tundra, forests, grasslands, and deserts. The plants and animals of each biome have traits that help them to survive in their particular biome . ... Each biome has many ecosystems.