Smiling or laughing in a smug, self-satisfied, or disrespectful way; showing contempt or amusement at someone else's expense.
From 'smirk,' possibly from Old English 'smearcian' meaning 'to creep or sneak.' The modern sense of smug satisfaction developed in the 1500s.
A smirk is a microexpression—it lasts only a fraction of a second, which is why lie-detectors and poker players watch for it: your true contempt leaks out before your conscious mind can hide it.
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