In vitro, in utero, these are science terms that have become commonly known. In vitro means studies in cells, like using test tubes, or a test for a fetus in the womb in the case of in utero.

Studies done in feces - yes, excrement - haven't really had a name, they though are common in gut bacteria analyses. Now they might, thanks to UNC School of Medicine scientist Aadra Bhatt, PhD, and colleagues; in fimo. Their proposal is published in the journal Gastroenterology.

Why, you might ask, do we need a scientifically accurate term based in Latin for the study of poop?  And if feces is too common, why not in feco? 

First, many scientific words are based in Latin because it's a "dead" language and therefore not easily subject to changing definitions colloquially. Second, the microbiome is so popular it is bordering on populism, with yogurt companies and supplement marketers claiming their probiotics will help with weight gain, eating disorders, cancers, gut diseases, and even autism. That leads to a gold rush into fields of study, which has happened with the microbiota. Which means the papers that result will need a latin name to sound more serious than "fecal" or "poop."


The world of cell phone texting is was ahead of science on this one, as the poop emoji shows. Look for in fimo studies of poopernatant samples to show up in journals soon. Unless competitors decide they don't want this to be popular lest it lead to more authority and therefore grant success.

When Bhatt set out to create a proper term, she enlisted Luca Grillo, PhD, a classics professor at Notre Dame, to help investigate the Latin roots of the word “manure.” Turns out, those pesky Romans had no less than four Latin terms for “manure” – laetamen, merda, stercus, and fimus.

Bhatt and Grillo traced laetamen to the Latin root laetus, which means “fertile, rich, happy.”

“For all its cheerful associations with joy,” Grillo said. “We had to resist the temptation to use ‘in Laetamine’ as our term of choice because it seems to have been more related to farm animal dung.”

Merda also didn’t smell right. It’s remained unchanged in Romance languages as a reference to poop – merde in French, mierda in Spanish, and merda in Italian – possibly derived from a root word smerd/smord, from which came the Old English derivatives “stinkan” and the current English words of “stink” and “stench.”

With two terms down the drain, Bhatt researched stercus and fimus. Both are older than laetamen and were never used to refer to stench. Bhatt and Grillo found that the word stercus was used broadly in ancient times, including as a term of abuse. It also seems to share the root word from which “scatology” originated. And scatology refers to “obscene literature.”

Originally, Romans used the term fimus less than stercus, and fimus seemed to refer strictly to the use of manure in agriculture. But, the key Roman writers Virgil, Livy, and Tacitus used fimus and never stercus.

“Fimus, then, with its technical accuracy and literary ring made us opt for “in fimo” as our scientific term of choice for the experimental examination of excrement,” Bhatt said.

Sticks in the mud of modernity might ask, “why not just use ‘fecal’ or ‘in feco?’”

Because both are wrong. Grillo said, “Faex never meant “excrement” in Latin, and its derivative, ‘feces,’ did not enter English usage until the 17th century, when it first referred to the dregs at the bottom of a wine cask or other storage vessels.”

And so, Bhatt and colleagues – including UNC co-author Matthew Redinbo, PhD – have been using “fimus” and “in fimo” at international academic conferences to what they say are rave reviews. Plus, just as some scientists have fun with their naming of model organisms – such as “Dumpy” for a mutant model of the classic worm C. elegans – Bhatt and colleagues have devised a playful term for the active enzymes they extract from their in fimo samples: poopernatant.