i'm feeling a little chalant...

Intellectually I know that "nonplussed" means perplexed, bewildered, to be thrown by something. But it sounds so much like "nonchalant" that whenever I read or write the word "nonplussed" it doesn't mean to me what it ought to.

Possibly because if one were "plussed"--although that's not a word in that sense, but then neither is "chalant"--if one were "plussed," I feel like it ought to be a synonym for "perturbed."

Fortunately English isn't based on what I feel like words should mean. It still throws me, though. (One might say I was...nonplussed.)