mortar-board

n (usu black) cap with a stiff square top, worn by certain university students and teachers on formal occasions （通常为黑色的）方顶帽, 学位帽（某些大学师生在隆重场合戴的）.

morose, morose-ness, morosely, morpheme, morphia, morphine, morphological, morphology, morris dance, morris dancer, morris dancer., morrow, Morse, morsel, mortal, mortal sin, mortality, mortality table, mortally, mortar, mortgage, mortgagee, mortgager, mortgagor, mortician, mortification, mortify, mortise (also mortice), mortise lock, mortuary, mosaic, Moscow, moselle, mosey, Moslem, mosque, mosquito, mosquito-net, moss, moss-grown,