Merriam-Webster's Word Central

April 24, 2016

biosphere (noun): \BYE-uh-sfeer\
What does it mean?: : the part of the world in which life can exist
How do you use it?: Students will be studying different parts of the terrestrial biosphere including deserts, tundras, wetlands, grasslands, tropical rainforests, deciduous forests, and coniferous forests.
Are you a word wiz?: "Biosphere" resulted from combining the word "sphere," which can be used to refer to a globe-shaped body as well as a model of the earth, and the combining form "bio-." What do you think the "bio-" in "biosphere" means?

A. life : living organisms or tissue

B. an area of knowledge that is an object of study : science

C. land as distinguished from air and sea : ground

D. origin : basic source or cause

The "bio-" in "biosphere" means "life" or "living organisms or tissue." This combining form, which is sometimes in the form "bi-," can also mean "biographical." Between these two meanings "bi-" or "bio-" plays a part in a number of words including "biology" and "biography." "Sphere" plays a part in words like "atmosphere" and "hemisphere."