Offensive self-satisfaction and complacency.
Offensive self-satisfaction and complacency — an irritating, self-congratulatory contentment, often about being right.
Offensive self-satisfaction: an irritating, self-congratulatory contentment, often about being right or virtuous. It centers on complacency and a sense of superiority (not appearance, like vanity, nor doom-courting overreach, like hubris), and is defined heavily by how it reads to observers — the word is almost always used by an outsider describing someone they find insufferable (“wipe that smug look off your face”). Lower-key and more everyday than hubris; the smug person feels validated while everyone else is annoyed.
From smug (1550s, “trim, neat, spruce”), probably from Low German smuck “neat,” related to German Schmuck “ornament.”
A clear shift from “neat / spruce in appearance” (1550s) to “self-satisfied”: the “self-satisfied air” sense is from 1701, extending the “smooth, sleek” sense. The appearance meaning faded and the complacency meaning became dominant. No reliable recent-generation shift.