SG Heritage Dictionary

Epidemical [Adjective] Webster's Dictionary 1913

1. Common to, or affecting at the same time, a large number in a community; -- applied to a disease which, spreading widely, attacks many persons at the same time; as, an epidemic disease; an epidemic catarrh, fever, etc. See Endemic.

2. Spreading widely, or generally prevailing; affecting great numbers, as an epidemic does; as, epidemic rage; an epidemic evil.

Epidemically [Adverb] Webster's Dictionary 1913

In an epidemic manner.