Reotifloation of instrument. In English law. To rectify is to correct or define something which ls erroneous or doubtful. Thus, where the par-ties to an agreement have determined to em-body Its terms in the appropriate and con-elusive form, but the instrument meant to efTect this purpose (e. g., a conveyance, set-tlement, etc.) is, by mutual mistake, so framed as not to express the real intention of the parties, an action may be brought in the chancery division of the high court to have it rectified. Sweet