After all that antiquare/antiquate nonsense, I just needed a simple happy word: Egregious.
Egregious derives from Latin "ex" and "grege" for literally "out of the flock", or poetically, "rising above the flock" or pre-eminent, outstanding. Of course that has good overtones, but a mere swing of the pendulum and some time later during the Middle Ages (of course!) we get the exact opposite meaning. That standing out is a bad thing, a glaring or conspicuous in its error. Archaically, it still retains the original meaning of exceptional, but no one would believe that usage as anything more than irony, so the the negative connotation it is.
Failure to use the subjunctive tense is no longer the egregious grammatical error that it once was, although it should be. While sight-reading the new piece, she mispronounced all the Latin, breathed in the middle of words, and didn't observe the subito piano marking in time to refrain from being the unintended soloist, evidencing her egregious musicianship. Never me! Plaintiff's counsel's arguments contained egregious misstatements of the law. Too easy. Enjoy!