epidemical
Adjective
1
: affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time
typhoid was epidemic
2
a
: excessively prevalent
b
: CONTAGIOUS sense 4
epidemic laughter
3
: characterized by very widespread growth or extent : of, relating to, or constituting an epidemic
the practice had reached epidemic proportions
Source