preclude
1. [ verb ] keep from happening of arising; have the effect of preventing
Synonyms: prevent forestall forbid foreclose
Examples:

"My sense of tact forbids an honest answer"

Related terms: stop debar thwart save obstruct obviation
2. [ verb ] make impossible, esp. beforehand
Synonyms: rule_out close_out
Related terms: obviate
Similar spelling:   prickle
  preclusive
  priceless
  preclusion
  prickly
  prickleback
  Pricilla