noun
life; the world of living things
Refers to the biological world or the realm of living organisms, often in contrast to the non-living world.
生物界には多様な種が存在する。
Diverse species exist in the world of living things.
自然界 is the natural world including both living and non-living things, while 生物界 focuses specifically on living organisms.
Compound of 生物 (living thing) and 界 (world, realm).