If you prearrange something, you plan or arrange it before the time when it actually happens. When you prearrange your funeral, you can pick your own flowers and music
{f} arrange beforehand; put in order beforehand; prepare in advance; make an agreement beforehand
You use prearranged to indicate that something has been planned or arranged before the time when it actually happens. Working to a prearranged plan, he rang the First Secretary and requested an appointment with the Ambassador. planned or decided before