JM sent this in a while ago (thanks!) and I just rediscovered it in my mailbox ... from the Christian Science Monitor:

With the news pages and airwaves filled lately with reports of a possible "pandemic" of bird flu, some people are turning to their dictionaries for clarity on the distinction between "pandemic" and "epidemic."

Some dictionaries seem to make the distinction as clear as mud.

"Pandemic" comes from Greek roots, "pan," meaning "all" or "total" (as a panoply is a complete suit of armor) and "demos," meaning "people." "Pandemic" means, most originally and literally "of all the people." It's become a bearer of bad tidings because it's now used almost exclusively as a short form of "pandemic disease" - meaning one that breaks out seemingly everywhere all at once, affecting "all the people."

The Spanish influenza of 1918 is an oft-cited example. It's thought to have been called this not because it originated in Spain but because Spain, as a neutral party during World War I, wasn't censoring its news media at the time and so was the first major country to report on the outbreak. The Spanish themselves, meanwhile, reportedly referred to the disease as "the French flu."

The Oxford English Dictionary defines "pandemic" first as "general, universal," and then gives a second sense: "Of vulgar or sensual love." It cites a line from the English poet Shelley: "That Pandemic lover who loves the body rather than the soul is worthless."

Meanwhile, back at the department of public health, "epidemic" is being used to describe an outbreak of disease among many people in a given place within a given time period. One way to think of it is that "epidemic" is local, and "pandemic" is global.

There's a third element of this discussion, "endemic," used as an adjective and much less often as a noun, to refer to diseases considered regularly present in a community but "generally under control," as my Webster's has it. The "en" prefix means "in" – an endemic disease is one "in the people." If "pandemic" and "epidemic" recur to acute episodes, where "everyone" seems to be getting sick, "endemic" refers to chronic conditions of public health. "Endemic" also has a more benign meaning, similar to "indigenous" or "native" – certain plants or animals may be said to be "endemic" to a given place.

Of these three, "epidemic" may be the one most commonly used, but it's the one I find hardest to get a grip on. It's because of that quirky "epi" prefix, common enough in words of Greek derivation, but not easily explained in English with a single term.

"Upon" is one rendering for "epi." It seems to suggest that which is on top of something else. An epidemic might thus seen as something "upon the people," that is, prevalent, or "visited upon" the people. "Epigraphy" ("writing upon [buildings]), for instance, is a fancy term for inscriptions collectively, or their study.

Another "epi" is the "epicycle." In the complexities of Ptolemaic astronomy, charts of the heavens showed cycles and epicycles, orbits within orbits, as stargazers invented ever more complex explanations for the movements of the planets, before it was understood that they revolve around the sun, not the earth.

And for a brief moment when I was in the fourth or fifth grade, it seemed the height of sophisticated humor for some kids in class to tease the less well read by taunting, "Your epidermis is showing" – the epidermis being the normally visible outer layer of the skin.

There's another "epi" much in the news in the case of earthquakes, which is "epicenter." An epicenter is not the exact place where an earthquake occurs, which is generally below the surface. Rather it's the area of the earth's surface directly above that place.

Some people, though, use "epicenter" as if it were an intensified form of "center": the "epicenter of the new media revolution," for instance, as one online guru has it.

So, too, "penultimate," the one before the last, is sometimes used to mean "beyond the ultimate," whatever that would mean. But the "pen" particle is from Latin meaning "almost," as in peninsula ("almost island"). Evidently what's being sought here, though, is a term for "the truly extraordinary."

The lessons here? Words have meanings. Fancy particles from Greek or Latin need to be handled with care. Otherwise verbal confusion may become pandemic.

... as I write/cut-and-paste this, coincidentally, there's a thing on Fox News about the impending 'pandemic' which is apparently "decimating" Asia ...