What's the difference between i.e. and e.g.?
1530s "gloomy," from Latin morosus "morose, peevish, hypercritical, fastidious," from mos (genitive moris) "habit, custom" (see moral (adj.)). In English, manners by itself means "(good) manners," but here the implication in Latin is "(bad) manners." Related: Morosity.