Definition of "germ theory" []

• The doctrine holding that infectious diseases are caused by the activity of microorganisms within the body. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Both Claude Bernard and Virchow had expressed their respective ideas before Robert Koch's discovery of the tubercle bacillus in 1882 won the decisive vic - tory for the germ theory of disease."