Definition of estoppel
In 1628, the great jurist Edward Coke (pron. "Cook") put it best:
"Estoppe" commeth of the French word estoupe, from whence the English word stopped: and it is called estoppel or conclusion, because a man's owne act or acceptance stoppeth or closeth up his mouth to allege or plead the truth
Sometimes, you "speak now or forever hold your peace": that is one kind of estoppel.Franchisees buying an existing location and assuming a lease or sub-lease of real property will ask for an Estoppel Letter from the Landlord since they are not going to simply take the word of the selling franchisee that the lease is paid up to date and in full force. In New York the standard form retail space lease has an "Estoppel" provision stating that the Tenant will provide an Estoppel Letter to the Landlord or his designated agent upon request. Such a request will come about if the landlord wants to sell or refinance the building.