You don’t hear the word “chauvinism” as much as you did a while back, when “male chauvinist” was a common epithet. As you probably know, “male chauvinism” is the belief that males are inherently superior to females. It was primarily applied to men — that is, human males, although I suppose a true believer might extend the notion to any species. Any careful examination of the relative dominance (male chauvinism is all about dominance) of males breaks down pretty quickly if you study, say, spiders or bees, but as a belief, chauvinism of any sort, male or otherwise, is generally pretty resistant to actual evidence.
Male chauvinism was first mentioned in 1935, in the play Till the Day I Die by Clifford Odets. But chauvinism itself goes back a bit further. The word is an eponym — that is, it’s based on a person’s name. In this case, the person is Nicolas Chauvin. He was a French soldier who was a Bonapartist to a fault; he believed in Napoleon and in France being an imperial power led by an authoritarian leader. Chauvin was badly wounded in one of the Napoleonic wars, and received only a tiny pension. Even the other Bonapartists ignored and forgot about him. Nevertheless, he maintained his steadfast devotion, believing Napoleon was going to bring glory to France even when it was getting to be quite obvious nothing of the sort was going to happen.
The word “chauvinism” was first popularized in an 1831 play, La Cocarde Tricolore, by the Cogniard brothers — they were ridiculing the large number of Napoleonic veterans in France who were aggressively — and blindly — patriotic. Chauvin himself was portrayed as a young soldier in Napoleon’s army.
There were other stories about Chauvin, though. One was that he served in the “Old Guard,” which was the central unit of Napoleon’s imperial guard. They were surrounded in the battle of Waterloo, and the story went that Chauvin shouted “The Old Guard dies but does not surrender!” This almost certainly didn’t happen; the commander of the Old Guard at the time was Pierre Cambronne, who did shout something, but a number of independent sources attested that what he actually yelled was “Merde!”
The word “chauvinism” became pretty common in English by the 1870s, and at the time it was exclusively used to mean excessive, unexamined patriotism. The journal American printed an article in 1883 noting that “educated men are supposed to see the difference between patriotism and Chauvinism.” Note that at the time, “Chauvinism” was still capitalized.
Over the next decades, chauvinism lost its capital “C”, Nicolas Chauvin was generally forgotten (again), and usage expanded to include any unwavering belief in a cause, a group, an idea, or what have you, especially if that belief involved prejudice against somebody else. It was used in “scientific chauvinism” in 1955, “cultural chauvinism” in 1975, “human chauvinism” in 1973, and even “female chauvinism” in 1970. Carl Sagan even came up with this in 1974: “A carbon chauvinist holds that biological systems elsewhere in the universe will be constructed out of carbon compounds…”
Probably the key aspect of any kind of chauvinism is that it resists evidence. You could presumably point out to Nicolas Chauvin that Napoleon’s brief reign hadn’t exactly covered France in glory, but it wouldn’t change his mind in the least. To a real chauvinist, real life and actual evidence just don’t matter. That’s probably appropriate for a belief that, if you recall, was popularized in two plays. Not only that, but as far as anybody can tell, there’s no evidence that “Nicolas Chauvin” ever really existed at all!
