Q: Why has “epidemic” become so widespread? I understand its metaphorical use (“an epidemic of Elvis impersonators in Vegas”), but now all sorts of medical “conditions” are being termed epidemics—obesity, drug abuse, even chronic pain.
A: The word “epidemic” is used so often to describe so many things that it’s lost much of its force.
The news is full of “epidemics” of football injuries, drug overdoses, mortgage fraud, accidental shootings, narcissism, loneliness, and cellphone thumb.
But to be fair, the word was never very specific, even in its medical sense. So while “epidemic”—both adjective and noun—is undoubtedly overused and suffering from exhaustion, it’s not being misused.
When “epidemic” entered English as an adjective in the early 17th century, it had a strictly medical meaning, but figurative uses soon appeared.
A disease was “epidemic,” according to the Oxford English Dictionary, if it was “prevalent among a people or a community at a special time, and produced by some special causes not generally present in the affected locality.”
(The OED takes its definition from The New Sydenham Society’s Lexicon of Medicine and the Allied Sciences, 1879.)
The OED says the adjective was first recorded in 1603, as “epidemick” and “epidemich,” in A Treatise of the Plague, by Thomas Lodge, an Elizabethan physician:
“Popular and Epidemich, haue one and the same signification; that is to say, a sicknesse common vnto all people, or to the moste part of them.” (We’ve expanded the citation.)
The adjective was borrowed from the French épidémique, which in turn was derived from the French noun form, épidémie.
English had long had a noun form “epidemy,” borrowed from French in the late 1400s, but it was replaced by the modern noun “epidemic” in the late 1700s.
The French took the noun from the late Latin word epidemia, which came from the ancient Greek epidemios, whose roots are epi– (among, upon) and demos (people).
Interestingly, the Greeks didn’t originally use epidemios in a medical sense. It first meant something like “in one’s country” or “among one’s people.”
In the Odyssey, probably composed near the end of the 8th century BC, Homer used epidemios to mean “who is back home” and “who is in his country,” according to two French scholars, Paul M. V. Martin and Estelle Martin-Granel.
In their essay “2,500-Year Evolution of the Term Epidemic,” published in 2006 in the journal Emerging Infectious Diseases, the authors note that Plato, Xenophon, Demosthenes, and Socrates later used epidemios “for almost everything (persons, rain, rumors, war), except diseases.”
The physician Hippocrates, writing in the 5th century BC, was the first to adapt it as a medical term, according to the essay. He used the adjective “to mean ‘which circulates or propagates in a country.’ This adjective gave rise to the noun in Greek, epidemia.”
Since the mid-20th century, the authors write, the English word “epidemic” has been applied to both infectious and noninfectious diseases that affect “a large number of people.”
And it’s also used by journalists, according to the essay, “to qualify anything that adversely affects a large number of persons or objects and propagates like a disease.”
But this use of “epidemic” is nothing new. The OED’s examples of figurative uses date from the mid-17th century, beginning with “the Epidemicke trouble of our age” (from Edmund Waller’s A Vindication of the King, 1642).
And here’s another early example, from Nicholas Rowe’s tragic drama The Fair Penitent (1703): “Some Foe to Man / Has breath’d on ev’ry Breast Contagious Fury, / And Epidemick Madness.” (We’ve expanded the citation.)
The OED also has early examples for the figurative use of the noun, including this one from Sir Benjamin Brodie’s Psychological Inquiries (1856): “There are epidemics of opinion as well as of disease.”
And as we all know, there are lexical epidemics as well.
from Grammarphobia http://www.grammarphobia.com/blog/2016/06/epidemic.html