Prevent, anticipate, forestall can mean to be or get ahead of or to deal with beforehand, with reference especially to a thing’s due time or to its actual occurrence or to the action of another.
Prevent implies frustration (as of an intention or plan) or an averting (as of a threatened evil) or a rendering impossible (as by setting up an obstacle or obstacles).
Sometimes the emphasis upon hindrance (see PREVENT 2 ) is so strong that other implications are nearly lost, but in the sense here considered advance provision or preparation against something possible or probable is clearly implied.
Anticipate (see also FORESEE ) takes the place of prevent when merely getting ahead of another especially as a precursor or forerunner is implied.
Like prevent, anticipate sometimes suggests frustrating another in carrying out an intention or plan, but implies its prior performance or execution rather than interposition of obstacles to its performance.
Distinctively, the word implies dealing with (as by using, paying, or acting) in advance of the due time or proper order but it often involves another implication which can be gathered only from the context; thus, one anticipates a payment on a loan by making a payment before it is due; one anticipates his salary by spending its equivalent before it is earned.
Forestall, in what has become perhaps the less common meaning, carries over from its earliest sense so strong an implication of intercepting that it means merely to stop in its course.
But often the word loses most of its suggestion of intercepting and then implies beforehand action that serves to render a thing, and especially something inevitable, powerless to harm or merely useless.