[rjmill]

I knew it! Context clues typically imply the ("wrong") meaning, so I misinterpreted this word for a while until I used it out loud, and my pedantic family corrected me.

But so many usages of the word are vague, and the difference between "perplexed" and "ambivalent" is not super important in most stories. (Whoever is nonplussed is not likely to take action on the situation.)

I had a feeling that some authors were using it "wrong." The article does a good job of finding examples where the author's intent was clear. But it's nigh impossible to figure out the intent in most cases. It's fascinating how so many different interpretations can thrive, while not being important enough to correct in most cases.

In my head, "nonplussed" is equivalent to a blank stare. The described person is either not paying attention, or the situation went completely over their head.

[tremon]

Funny. In my head, nonplussed was near-synonymous with unimpressed. So in my interpretation they were neither not paying attention, nor in over their head -- but the blank stare remains nonetheless. That still closer to your interpretation than "baffled, perplexed" as it apparently originally meant.

[gms7777]

I always read it as meaning something like "unfazed" before seeing someone get corrected on it.

[SOLAR_FIELDS]

I also, from reading a lot of literature, took this meaning. I’ve never been a fan of the word though, probably partially because of the ambiguity being discussed here

[camdenreslink]

Another word that is often used incorrectly. "Ambivalent" doesn't mean "unruffled" or "unbothered". It actually means to have two (possibly strong) contradictory emotions. It's more like "bittersweet" or to be "of two minds".

[lupire]

But it can mean "unmoved"!

In a metaphorical physical sense where an object is immobilized by two opposing forces.

But it's direct. It's "both valences" ("valence is loosely like " value"), like in chemistry. "Ambi", which implies that there are only two possibilities, instead of "bi" which merely means 2 actual among many possible.