/ɪnˈfekʃn ||; ɪnˈfɛkʃən/noun1 [U] the act of becoming or making sb ill 传染；感染: A dirty water supply can be a source of infection. 不洁的供水可以成为感染疾病的来源。There is a danger of infection. 有感染病毒的危险。
2 [C] a disease or illness that is caused by harmful bacteria, etc and affects one part of your body （身体某部份的）感染: She is suffering from a chest infection. 她肺部受了感染。an ear infection 耳部感染
Infections can be caused by bacteria or viruses. An informal word for these is germs. 传染病的起因是感染了细菌(bacteria)或病毒(virus)。非正式场合用germ。