redhibitory defect

noun

in the civil law of Louisiana : a defect that renders a thing useless or so diminishes its usefulness or value that it must be presumed that the buyer would not have bought it or would have paid a lesser price if aware of the defect

a seller is deemed to know that the thing he sells has a redhibitory defect when he is a manufacturer of that thing

—Louisiana Civil Code

called also redhibitory vice

Note: A seller that knows of a redhibitory defect but omits to declare it, or that declares the thing to have a quality he or she knows it does not, is liable for return of the purchase price with interest and for damages, other expenses, and reasonable attorney's fees.