These words refer to a facial expression in which the mouth is silently widened and its corners are upturned in order to convey such emotions as affection, amusement, confidence, irony, polite approval or disdain. Smile is the most general here, referring to any such expression regardless of the emotion being conveyed: giving the child a tender smile ; swaggering down the street with a bright smile ; unable to suppress a smile at his naïveté; the bitter smile he wore during his opponent’s rebuttal. Because the expression itself suggests pleasure or approval more readily than other emotions, the word can even refer to the stereotyped mannerism that is put on automatically for other people in the absence of sincere emotion of any sort: the maddening and invariable smile that some air hostesses wear in response to every request or complaint.

The remaining words restrict themselves in reference to particular emotions or situations that motivate the smile . Grin indicates a greater widening of the mouth than smile , especially one that exposes the teeth, and suggests spontaneity, greater emotional intensity, and implies friendly warmth, pleasure, mirth or high-spirited amusement: giving her his best devil-may-care grin ; the grin with which she greeted her old school-friend. The word is derived from a root referring to howling or groaning, and the word is sometimes used for a less amicable or even ferocious baring of the teeth; the grin of a snarling wolf; the wounded soldier’s grin of pain. In this use, the word may be a colourful substitute for grimace, which is more precise.

Simper and smirk are sometimes equated as indicating the same sort of silly or fatuous expression, but strikingly different connotations surround each word. Simper suggests smugness and self-righteousness and may even imply primness: the Wife of Bath’s complaisant simper ; a sort of mutual admiration society in which they could exchange simpers of superiority as they faced the uninitiated. Smirk may be used with precisely these same overtones. But where simper may suggest the reflection of an abiding self-consciousness and inward feeling of hypocritical superiority, smirk suggests more often a momentary outward expression of derision or hostility: a teacher who tricks his students into giving incorrect answers and then greets them with a smirk ; a man in handcuffs regarding his captors with a smirk . Leer is a more forceful word than smirk and suggests a glance and grin showing cunning, viciousness or lasciviousness: slouched against the wall leering at unescorted girls.