词根radi的意思是：光线,辐射。来源拉丁语 radix /radius/radiare 光 / 辐射，ray，rad，radio为radi的变体。它相应的希腊语词根为：-acti(n)-,-actino- 光,光线,呈放射状的,放射线的。同源词：1.radiant adj. 容光焕发的；辐射的radiate v.放射；散发radiation n.放射，散发；放射物radiator n.散热器；电炉radium n.镭radioactive adj.放射性的You had the most radiant smile as you crossed the finish line.你超过终点线进绽放出了最灿烂的笑容。2.radar n.雷达，无线电探测器radar fence /screen 雷达网radar homing 雷达导航的radar installation 雷达装置follow the flight of an aircraft by radar 通过雷达追踪飞机The ship's radar scanned the sea ahead.船上的雷达扫描了前方的海域。3.radial adj.光线；半径的radial tire 子午线轮胎The white marble floors were inlaid in a radial pattern of brass.白色的大理石地板镶嵌在铜质的放射形图案中。4.radius n.（圆、球的）半径；半径范围；（活动等的）范围（由中心所发的光能到达的范围）every tree within a radius of two miles 周围2英里的所有树木radius of action 行动范围Nigel has searched for work in a ten-mile radius around his home.奈杰尔一直在他家周围10英里的范围内找工作。5.radiance;-ancy n.闪烁；发光6.radio n.无线电报；无线电话；无线电广播；收音机7.radioactive adj.有辐射能的；放射性的（主动辐射的）《active = 主动的》8.radioactivity n.放射性；放射现象9.radiology n.放射学；应用辐射学；放射线科《logy = stydy》10.radiotelephone n.无线电话（机）《telephone = 电话机》11.radiotherapy n.X光治疗法；放射线治疗法《therapy = 治疗法》12.irradiate v.照耀；发出；照射（将光线投射在...上）《ir- = in- = on》It's safe to eat foods that have been irradiated to prolong their shelf life.食用经过辐射杀菌处理、延长了保质期的食品是安全的。13.irradiation n.发光；光线；照射14.irradiant adj.发光的；灿烂的15.irradiance n.发光；光辉；灿烂
