Because I always fuck up nonplussed and think it means "irritated" instead of "perplexed," I'm going to post its etymology to Slog. And then maybe I'll remember.
nonplus 1580s (n.), properly "state where 'nothing more' can be done or said," from L. non plus "no more, no further." The verb meaning "to bring to a nonplus, to perplex" is attested from 1590s. Related: Nonplussed.
We now return you to your regularly scheduled police chiefs and crazy Christians and velvet weeping Jesus dreamcatchers.