Scoff, jeer, gibe, fleer, gird, sneer, flout can all mean to show one’s scorn or contempt in derision or mockery.
Scoff stresses insolence, irreverence, lack of respect, or incredulity as the motives for one’s derision or mockery.
Jeer carries a stronger implication of loud derisive laughter than scoff, it usually connotes a coarser and more vulgar or, at least, a less keenly critical attitude than scoff .
Gibe stresses taunting, often in derisive sarcasm, sometimes in good-natured raillery.
Fleer throws the emphasis upon derisive grins, grimaces, and laughs rather than on utterances.
Gird implies an attack marked by scoffing, gibing, or jeering.
Sneer carries the strongest implication of cynicism and ill-natured contempt of any of these terms; it often suggests the use of irony or satire the real purport of which is indicated by an insultingly contemptuous facial expression, tone of voice, or manner of phrasing.
Flout may imply any of the actions suggested by the preceding terms, but it carries a heightened implication not only of disdain and contempt but of refusal to heed or of a denial of a thing’s truth or power.