smirk
verb no object
«…で» にやにや［にたにた］笑う «at»
e.g. he smirked in triumph.
noun
うすら笑い, にやにや笑い.
e.g. Gloria pursed her mouth in a self-satisfied smirk.
DERIVATIVES
ORIGIN
Old English sme(a)rcian, from a base shared by smile. The early sense was ‘to smile’; it later gained a notion of smugness or silliness.