1
- a widespread occurrence of an infectious disease in a community at a particular time（传染病的）流行, 传播：
a flu epidemic.
流感的流行。
1.1
- a disease occurring in such a way流行病。
1.2
- a sudden, widespread occurrence of a particular undesirable phenomenon蔓延; 盛行; 猖獗：
an epidemic of violent crime.
暴力犯罪的猖獗。
词源
early 17th cent. (as an adjective)： from French épidémique, from épidémie, via late Latin from Greek epidēmia 'prevalence of disease', from epidēmios 'prevalent', from epi 'upon' + dēmos 'the people'.