Pneumonia: An acute or chronic disease marked by inflammation of the lungs and caused by viruses, bacteria, or other microorganisms and sometimes byphysical and chemical irritants.

• 肺炎:一种急性或慢性疾病,特征是肺部发炎,由病毒、细菌或其它微生物引起,有时由物理和化学的刺激物引起。