If something is modified, it has been changed. Only modified trucks participate in Monster Truck Rallies — ones that have had their regular tires replaced with monster tires.
Modified is the past tense of modify, from the Latin modificare, meaning “to limit,” or “restrain.” Modified anything has been altered. A modified schedule has been reshuffled, a modified diet limits your regular calorie intake, and a modified workout lets you sit on your couch and watch Jack LaLanne sweat.
adj changed in form or character
changed in order to improve or made more fit for a particular purpose
restricted in meaning; (as e.g. `man' in `a tall man')
limited or restricted; not absolute
characterized by variety