'Estoppel' definitions:

Definition of 'estoppel'

(from WordNet)
noun
A rule of evidence whereby a person is barred from denying the truth of a fact that has already been settled

Definition of 'Estoppel'

From: GCIDE
  • Estoppel \Es*top"pel\, n. [From Estop.] (Law) (a) A stop; an obstruction or bar to one's alleging or denying a fact contrary to his own previous action, allegation, or denial; an admission, by words or conduct, which induces another to purchase rights, against which the party making such admission can not take a position inconsistent with the admission. (b) The agency by which the law excludes evidence to dispute certain admissions, which the policy of the law treats as indisputable. --Wharton. --Stephen. --Burrill. [1913 Webster]