On: Nonplussed

[foobarqux]

Those people are using it incorrectly.

[pbhjpbhj → foobarqux]

Language is ultimately about usage. The dictionary I checked with confirmed this meaning as a US neologism, I'm in the UK.

You could class this usage as "perplexed" but with a specific flavour of 'perplexity at the unimpressive nature of the subject'.

[rafcavallaro → pbhjpbhj]

US colloquial usage - where the original, subtle UK usage goes to die; see also "presently," and "beg the question."