the principle which precludes a person from asserting something contrary to what is implied by a previous action or statement of that person or by a previous pertinent judicial determination:the case had been one of estoppel [count noun]:that fact is not sufficient to raise an estoppel
Origin:
mid 16th century: from Old French estouppail 'bung', from estopper(see estop)
estoppel in other Oxford dictionaries
Definition of estoppel in the US English dictionary