'Ferment' vs. 'Foment'

You might associate the word ferment with making yogurt, kimchi, or beer and foment with inciting violent acts, but it’s easy to see how they might be confused for each other. For one thing, neither word is part of common everyday vocabulary, and they resemble each other in spelling and pronunciation, but that’s not the whole story here: these words, in fact, share a core meaning that connects the ideas they represent beyond the coincidence of resemblance.

'Foment' is ultimately from the Latin 'fovēre,' meaning “to heat” or “to soothe.”

The Origin and Usage of 'Ferment'

The connection with comestibles and beverages is clear from the origin of ferment, which comes from the Latin word for “yeast,” fermentum, from the verb fermentare “to cause to rise or ferment,” but the word’s ultimate Latin root, fervēre, means “to boil” which is also the root of fervent.

“Heat,” therefore, is at the root of ferment. In fact, in Noah Webster’s 1828 dictionary, his definition of the rarely used noun ferment makes the etymological connection quite clear:

1. A gentle boiling; or the internal motion of the constituent parts of a fluid.

Indeed, ferment as a noun was used in Samuel Johnson’s 1755 dictionary definition of yeast:

the ferment put into drink to make it work; and into bread to lighten and swell

It was understood from ancient times that covering the liquid of grapes or of mashed grains produced wine and beer, but only more modern science broke down the process of alcoholic fermentation to show the conversion of sugars by yeasts. Using a derivative of the word meaning “to boil” to refer to this process stemmed from the bubbles produced during the conversion to alcohol—it looked like it was boiling. Fermentation does in fact produce heat, and the temperature of the liquid when mixed with yeast is critical, but it appears the word was used more for the resemblance of fermenting liquid to boiling liquid than from an understanding of the metabolic processes early brewers were witnessing.

Modern Usage of 'Ferment'

Today, the verb ferment has a common literal meaning as well as a common figurative meaning. Its literal use, “to undergo or to cause to undergo fermentation,” relates to the process of making yogurt, beer, wine, etc.

Its figurative use, “to be in a state of agitation or intense activity,” can express action or change in ideas, expression, or performance:

Rhythm and blues began to ferment into what would one day become the vintage Motown sound in Detroit's Paradise Valley and Black Bottom.
— Ryan Matthews and Watts Wacker, "Deviants, Inc," Fast Company, 28 February 2002

As a noun, ferment can be used to mean “enzyme” (as Samuel Johnson did in the above definition), but is more commonly encountered in the meaning “a state of unrest,” a synonym of “agitation.”

The adjectives most frequently used with the noun ferment show that its use meaning “an enzyme” is long past, and that today this word is connected more with ideas than with ingredients:

political

intellectual

social

cultural

artistic

religious

revolutionary

Note that, like other two-syllable English words that are both nouns and verbs (think of rebel, protest, or record) the noun ferment is pronounced differently from the verb; the noun typically has stress on the first syllable, \FER-ment\ and the verb has stress on the second syllable, \fer-MENT\.

Sometimes, this noun is used to describe extreme worry or unrest:

At the same time it is couched in so unfortunate a manner, and certain phrases in it are of so provocative a character, that its publication would undoubtedly lead to a most dangerous state of feeling in this country. There would be such a ferment, sir, that I do not hesitate to say that within a week of the publication of that letter this country would be involved in a great war.
— Arthur Conan Doyle, The Second Stain, 1904

The proposal sank like a stone in Washington but caused great ferment overseas, particularly among countries that would be unhappy if Beijing and Washington acted upon the idea.
— Richard C. Bush, The United States and China, brookings.edu, 11 October 2011

Sometimes, on the other hand, it expresses a positive mental energy:

The resulting carnival of expatriate intellectual ferment and commercial rapacity provided the setting for Palladio's coming of age as an architect.
— Dave Hickey, Harper's Magazine, April 2003

The Origin and Usage of 'Foment'

Foment also came to English from Latin, from fomentum meaning “compress” (“a folded cloth”) and ultimately from fovēre, meaning “to heat” or “to soothe.” Its original meaning in English was “to apply a warm substance to,” and it was still in use when Noah Webster published his dictionary in 1828:

1. To apply warm lotions to; to bathe with warm medicated liquors, or with flannel dipped in warm water.

This meaning has become obsolete. Another English word that has fovēre as its ultimate Latin root is fomite, “an object that may be contaminated with infectious organisms and serve in their transmission,” which comes from the Latin word meaning “kindling wood,” conveying the idea that contact with microscopic contamination can lead to the “fire” or spread of disease—a similar image, if you think about it, to the “fire” or “heat” of ideas that can ferment into a state of agitation.

Modern Use of 'Foment'

Today, we use foment with the meaning “to promote the growth or development of,” a synonym of rouse and incite as in “to foment a rebellion.”

Having failed last year to address the danger that Trump represents, the Party bears responsibility for Trump this year being in a position to foment insurrection.
— Jelani Cobb, The New Yorker, 8 January 2021

This meaning is also close to inflame and, indeed, this is where foment intersects with the figurative use of ferment as well. It expresses distress, concerns, or ideas that are unsettled and impel action or change, a synonym of “to agitate" or "to excite.” Joe Biden used ferment in this way, adding it to a similar figurative use of brew that shows that English has turned the chemical changes that make beer and wine and liquor into potent metaphors:

When you have income inequality as large as we have in the United States today, it brews and ferments political discord and basic revolution.
— Joe Biden, 19 June 2019

In fact, foment is listed as a synonym of ferment in this sense, so these words, whose superficial resemblance to each other is just a coincidence, can nevertheless both express ideas that create more heat than light.