In a Word: A Pair of Parasites

Senior managing editor and logophile Andy Hollandbeck reveals the sometimes surprising roots of common English words and phrases. Remember: Etymology tells us where a word comes from, but not what it means today.

Parasites aren’t something we normally like to think about, unless you’re a parasitologist or a fan of Bong Joon Ho movies. So I’ll keep this exploration of parasite brief.

A lot of English words use the Greek prefix para-, which can mean “beside” (as in parable and paraphernalia) or “against or outside of” (as in paradox and parachute). In the case of parasite, it’s the former.

The second half of the word comes from the Greek sitos “grain, bread, food.” That isn’t a root we see much of in English. There are late-19th-century references to sitology as the branch of science concerned with the regulation of the diet, but today’s sitologists are more likely to be called nutritionists or dietitians.

Oddly, etymologists have been unable to trace sitos back any further than ancient Greek, so we don’t know why grain was called sitos.

I had believed — and perhaps you did too — that calling a person who takes more than they give a parasite was a metaphorical use of the sense “an organism that uses a host to grow or multiply in a way that harms the host.” But it’s really the other way around: A Greek parasitos was one who lived at the expense of another, literally someone who ate from the table of another, hence “beside + food.”

And that’s basically the sense we see of the word parasite when it is first recorded in English in the 16th century: a moocher or sponger or toady. The biological sense appeared about 100 years later.