epidemic (adj.)

"of or belonging to the people," especially "pertaining to the common people, popular, vulgar," 1822, from Latinized form of Greek dēmotikos "of or for the common people, in common use," from dēmos "common people," originally "district," from PIE *da-mo- "division," from root *da- "to divide." Originally in English it was used in reference to the simpler of two forms of ancient Egyptian writing (opposed to hieratic or hieroglyphic); the broader sense is by 1831. Used of the popular form of modern Greek since 1927.

"an epidemic disease," especially the plague, late 15c., ipedemye, impedyme, from Old French ypidime (12c., Modern French épidémie), from Late Latin epidemia (see epidemic (adj.)).