grimace

A grimace is a visceral, involuntary reaction that manifests as a sudden contraction of facial muscles. It differs from a frown, which is often a sustained expression of sadness or anger, by its fleeting, sharp nature and its strong association with physical repulsion or acute discomfort. It conveys a sense of internal struggle or an instinctive attempt to recoil from an unpleasant stimulus. When used as a verb, the word emphasizes the physical act of twisting the features. It is frequently employed in narratives to signal a character's silent reaction to bad news or a foul smell, serving as a non-verbal cue for disapproval or agony without the need for explicit dialogue.