طَيّ: ثَنْي doubling, fold(ing); rolling up, pleating, tuck(ing); bend(ing), flexing, flexion, turn(ing), flection

طَيّهُ، طَيّ هذَا، فِي طَيّه enclosed, attached, herewith

(تَحْتَ، فِي) طَيّ الكِتْمَان under the seal of secrecy, kept (secret), covered up, undisclosed, concealed, hidden