Back in, say, 1600 or so, if you were going to combine two things, you were probably very pleased to be able to choose between two relatively new words: “conflate” and “commingle.” “Conflate”, at least in the 1600s, meant “put together,” and “commingle” meant (and still means) “mix together.” Pretty close to the same thing, depending on just what sort of things you’re trying to blend or consolidate.
As time went on, two things happened. By the 1800s, the meaning of “conflate” had shifted a bit — it came to be used primarily in relation to words or ideas and fell out of usage for melding, unifying, fusing, or coalescing physical things. The other thing that happened was that by the 1800s it was perfectly obvious to anyone who was tracking word usage with a tool like Google’s NGram Viewer (admittedly very rarely used in the late 1800s) that “commingle” was a vastly more useful word than “conflate. In fact, by about 1870, usage of “commingle” was orders of magnitude more widespread than “conflate.” “Commingle” had clearly won.
Then about 1880 or so, usage of “commingle” started to decline a bit. It was still much, much more common than “conflate,” but by about 1915 or so it was used only about 20 or 30 times as often as “conflate”. This could have been because in the late 1800s writers like James Rendel Harris published articles in the American Journal of Philology containing riveting lines like this: “The two readings [ἐκεῖνος and αὐτός] are undoubtedly early, since they are conflated in Cod. D into ἐκεῖνος αὐτός.” Meanwhile “commingle” was championed by the likes of Edward George Earle Lytton Bulwer-Lytton, who used it in the 1848 book Harold, last of the Saxon Kings: “A yell of such terror, and woe, and wrath all commingled.”
I’m sure you remember Bulwer-Lytton; he’s the chap who came up with “the pen is mightier than the sword,” and is today immortalized in the Bulwer-Lytton Fiction Contest. That annual competition awards al prize to the opening sentence of the worst of all possible novels. it’s based on the opening line in Paul Clifford: “it was a dark and stormy night.” To make matters possibly worse for Edward, he didn’t even come up with the phrase. Washington Irving used it back in 1809 in A History of New York. The poor guy is taking heat more than a century after his death for bad writing that he plagiarized in the first place! His problems probably all started when he discovered his name includes “Lytton” twice: Edward George Earle Lytton Bulwer-Lytton. It would have made much more sense to amalgamate those two occurrences.
But to get back to commingle and conflate, usage of “commingle” kept declining steadily until about 1940, when it stabilized at a much lower level than previously. “Conflate” continued to be very rarely used, but then, in the 1960s, usage began to rise. By the late 70s “conflate” had caught up with the usage of “commingle,” and after that, the graph of common usage of ‘conflate” went nearly vertical. Today, “conflate” is far more common than “commingle.”
A couple of things might be going on with this. First, of course, words change in popularity. Take, for example, “yclept.” It was a perfectly useful word for many centuries, starting all the way back in Old English. It means “also called,” so you might say something like “‘commingle,’ yclept ‘mix’”. But for no particular reason other than looking weird because how often do you see English words beginning “y-c-l”, practically nobody uses it anymore. The second thing that might be going on with the reversal of fortunes between “commingle” and “conflate” is that while “commingle” kept its association with physical things you might be admixing, compounding, integrating, melding, or uniting, “conflate” became associated with words and ideas. Around the same time that “conflate” started to be used more and more, people’s daily activities — and here I’m talking about the vast blend of everybody’s activities in general — started to shift from manipulating physical work to “knowledge work” — that is, all you really work with is words, numbers, and ideas. So maybe “conflate” just began to have more day-to-day relevance than “commingle.” Besides, there must be at least one or two alternatives available to describe the process of alloying physical things. Not that I can think of them.
