An acute or chronic disease marked by inflammation of the lungs and caused by viruses, bacteria, or other microorganisms and sometimes by physical and chemical irritants.
Inflammation of one or both lungs, in which the air sacs (alveoli) become filled with liquid, which renders them useless for breathing. It is usually caused by bacterial (esp pneumococcal) or viral infection
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.
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