We don't have synonyms for estoppal yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are estoppel, estopped and estoppage.
(n) :
Misspelling of estoppel. [(common law) A legal principle in the law of equity that prevents a party from asserting otherwise valid legal rights against another party because of conduct by the first party, or circumstances to which the first party has knowingly contributed, making it unjust for those rights to be asserted.]
(n) :
Misspelling of estoppel. [(common law) A legal principle in the law of equity that prevents a party from asserting otherwise valid legal rights against another party because of conduct by the first party, or circumstances to which the first party has knowingly contributed, making it unjust for those rights to be asserted.]