rubric

n.成规，习俗；指示，指导

rub off, rub out, rub sb out, rub sth in/into sth, rub sth up, rubber, rubber goods, rubber plant, rubber stamp, rubber-neck, rubber-stamp, rubberize, rubberise, rubbery, rubbing, rubbish, rubbishy, rubble, rubella, Rubicon, rubicund, ruby, ruby wedding, RUC, ruche, ruched, ruck, rucksack, ruckus, ructions, rudder, ruddily, ruddiness, ruddy, rude, rudely, rudeness, rudiment, rudimentary, rue, rueful,