mindmap root((阻止)) prevent implies the existence of or the placing of an insurmountable obstacle: the blizzard ~ed us from going. preclude implies the existence of some factor that shuts out every possibility of a thing's happening or taking effect: an accident that ~ed a career in football. obviate suggests the use of forethought to avoid the necessity for unwelcome or disagreeable actions or measures: his resignation ~ed the task of firing him. avert implies the taking of immediate and effective measures to avoid, repel, or counteract threatening evil: deftly ~ed a hostile corporate takeover. ward off suggests a close encounter and the use of defensive measures: a hot drink to ~ a chill.