These words refer to the applying of force in a hostile way so as to repel or subdue any opposing resistance. Thwart suggests the outwitting of an enemy or the undoing of his plans: sending troops to thwart the rebellion. The word often implies the use of cleverness instead of violence to attain the enemy’s defeat and suggests action taken before the enemy himself has had time to move: the scheming villain whose designs on the helpless maiden were always thwarted before the final curtain. The word has recently appeared frequently in a psychological context, suggesting barriers that prevent the full realization of one’s natural endowments: a generous and receptive intelligence that was thwarted from attaining its full scope by bad training, poor schools and lack of opportunity.

Foil relates to that aspect of thwart that emphasizes the undoing of an enemy’s plan before any damaging action has been accomplished: foiling the assassination plot by placing on the throne a straw dummy dressed like the king. In some modern contexts, the word may sound melodramatic and old-fashioned. Balk relates to that aspect of thwart that emphasizes the imposing of barriers, but balk does not necessarily suggest the interruption of an otherwise natural or inevitable process: every effort at creative teaching balked by the reams of paperwork that had to be filled out each week.

Frustrate in its most general context suggests the confounding of an enemy by tactics short of an open confrontation in direct battle: frustrating Hannibal’s drive towards the sea by hemming in his troops and engaging them in inconclusive night skirmishes. Like thwart , it can suggest the undoing of an enemy’s plans before he can execute them, although in this case the result is less conclusive than with thwart , since here it can imply merely forcing the enemy into inaction or into holding his plans in abeyance: frustrating every effort the prisoner made at getting word to his confederates. When the situation of enemies is not involved, the word may suggest any sort of insurmountable obstacle that reduces someone to galling inaction: talented playwrights frustrated by the high cost of production and the coarse commercialism of the theatrical entrepeneurs.

Inhibit , like one aspect of frustrate , suggests the forcing of something into inaction rather than a complete routing of it: inhibiting the wage-price spiral by an increase in taxes. Both frustrate and inhibit , however, have gained currency in a psychological context for suggesting barriers that impede normal development or prevent the realization of natural desires. Frustrate here suggests an insoluble conflict between two forces working upon or within a person: frustrated by desires he believed it would be reprehensible to satisfy. Inhibit here specifically suggests the weakening or damaging of normal impulses: rules so rigid as to inhibit any calm development of self-assurance; learning to inhibit those antisocial impulses that would result in injury or harm to others.

SEE; confuse, hinder, subdue.