IPA: /ˌɛpɪˈdɛmɪkli/
KK: /ˌɛpɪˈdɛmɪkli/
In a way that relates to or resembles an epidemic, often referring to the rapid spread of something, such as a disease or trend.
The disease spread epidemically, affecting thousands in just a few weeks.
Epidemically → It is formed from "epi-" (meaning upon or over) and "demos" (meaning people) and the suffix "-ically" (meaning in a manner relating to). The word describes something that occurs upon or affects a large number of people, typically in the context of disease.
Think of something that spreads 'upon' ('epi-') a large group of 'people' ('demos') — that's why epidemically refers to something affecting many people.