Q: Do you have any comments regarding why a word or phrase can completely reverse its meaning over time. For example, “hoi polloi” went from meaning the exclusive classes to the unwashed masses.
A: In fact, “hoi polloi” has meant the masses or the common people since classical times. Some folks erroneously believe it originally meant the elite, but that’s not true.
This misconception is probably the result of confusion with “hoity-toity,” an old expression that means, among other things, pompous or self-important. I recently wrote a blog item that touched on the expression “hoi polloi.”
As for your larger question, it’s true that words and phrases can change in such a way that their modern meanings become the reverse (or nearly so) of the originals.
The word “nice” is a good example. At various times in the past it has meant foolish, overly fastidious, wanton, and profligate. In other words, not very nice.
And “cute,” back in the days when it was short for “acute,” meant shrewd or perceptive or calculating (though it has also meant bow-legged!).
“Sophisticated” once meant corrupted, and “silly” meant happy. Likewise, “awful” once meant deserving of awe; “terrible” meant terror-inducing; “wonderful” meant wonder-inducing.
So when you’re reading an 18th-century novel, it’s not surprising to find a magnificent cathedral described as “awful,” or a sudden catastrophe described as “wonderful,” or a fierce animal descrbed as “terrible.”
Why all this change? The reasons vary from word to word, but the short answer is that English is a work in progress.