rotor

n rotating part of a machine, esp on a helicopter 机器的旋转部分; （尤指直升飞机的）旋翼. =>illus at helicopter 见 helicopter 插图.

rosebush, rosemary, rosette, rosewood, rosin, rosiness, roster, rostrum, rosy, rot, rot-gut, rota, rotary, rotate, rotation, rotational, rotatory, rote, rote learning, rotisserie, rotten, rottenly, rottenness, rotter, rotund, rotunda, rotundity, rotundly, rouble (also ruble), roue, rouge, rough, rough house, rough luck, rough-and-tumble, rough-hewn, roughage, roughcast, roughen, roughly,