“In Fimo”: A Term Proposed for Excrement Examined Experimentally

Latin continues to provide exact and elegant expressions that have become standard in the international scientific community. Think of “in vitro” and “in vivo.” Here, we propose “in fimo” to indicate samples derived from human and animal excrement and examined scientifically. The importance of material extracted from excrement for study has recently become clear (e.g., ¹). We have proposed the “in fimo” terminology in a submitted manuscript and have been using it in international presentations, and it has been met with much favor. Here we explain the interdisciplinary rationale for our choice.

Romans were farmers, and when it came to manure they were second to no one. Indeed, the semantic field of “manure” is covered by no less than four Latin terms – laetamen, merda, stercus and fimus. Each noun carried different connotations, and each of these connotations has left a mark in current English. According to Servius (a 4th Cent. AD grammarian), “people commonly call laetamen the dung which gets spread across fields” (2). Servius rightly traced the origin of laetamen back to laetus, “fertile, rich, happy;” and laetus belongs to the same family as laetitia, “joy, gladness” (and hence “beauty, grace”), from which come the proper names Laetitia and Letitia. For all its cheerful associations with joy and happiness, we had to resist the temptation to use “in laetamine,” because it seems to have been more readily related to farm animal dung. And, importantly, laetamen became the standard technical term for manure only in Late Latin and is never attested before Pliny the Elder (AD 23–70; ³).

Merda indicated both human and animal excrement. But, to us, this was not a tenable option because of its most base and least scientific connotation, which has remained unchanged in Romance languages (e.g., merde in French, mierda in Spanish or merda in Italian). Merda possibly derived from a root *smerd/smord, from which come Old English “stinkan” and current “stink” and “stench.”

The choice, then, fell between stercus and fimus. Both are attested a couple of centuries before laetamen and escape the base connotation of merda, and both came to signify human and animal excrement alike. As a general term, stercus enjoyed a broad array of uses: it occurs among early religious language but was also employed as a term of abuse, a use Cicero disapproved (4). From stercus come “stercoraceous,” pertaining to excrement, and from the same root *sker/*skor derive also “scatology” a noun referring to “obscene literature.”

Fimus was initially less frequently employed and seems to have originally carried a more restricted meaning explicitly linked to agriculture. With time, however, it took on a literary flavor, and was favored by Virgil, Livy and Tacitus, in whose works stercus never appears. Fimus, then, with its technical accuracy and literary ring made us opt for in fimo.

One might ask why not simply stick with “fecal” or “in feco”? Both are incorrect, semantically and grammatically. Faex never meant excrement in Latin, and its derivative, “feces” did not enter English usage until the 17th century. Even then, “feces” meant the dregs remaining the bottom of a wine cask or other storage vessel.

Moreover, “in feco” is not a Latin expression (the correct form would be “in faece”).

Finally, “ex vivo,” another possibility, applies to any material collected from a human or model organism, not just excrement, and is therefore not appropriately specific.

Thus, we propose and have been employing “fimus” and “in fimo”, from the High Latin and used by Virgil, to mean excrement examined experimentally. However, to remain grounded in the whimsy that can accompany scientific naming [e.g., the model organism mutants Dumpy (5), Cheap Date (6), and Sonic Hedgehog (7)], we use the following term for active enzymes extracted from an in fimo sample: poopernatant.