orb
n.
mid-15c., "sphere, globe, something spherical or circular," from Old French orbe "orb, globe" (13c.) and directly from Latin orbem (nominative orbis) "circle, disk, ring, hoop, orbit," probably related to orbita "wheel track, rut," of unknown origin. Watkins suggests a connection with the root of orchid.A three-dimensional extension of a word originally describing two-dimensional shapes. Astronomical sense is in reference to the hollow spheres that carried the planets and stars in the Ptolemaic system. As a verb from c.1600. Orb weaver spider is first recorded 1889.
词根：orb = circle, track
来自拉丁语的orb 意为circle,track。
同源词：
1. exorbitant（脱离常规、轨道的ex(=out) + orb(=track,circle)）
adj.（价格、要求等）过高的，过分的
exorbitance n.（价格、要求等的）过高，过分
exorbitantly adv.过高地，昂贵地
Prices for butter and eggs were exorbitant during WW Ⅱ. 第二次世界大战期间黄油和鸡蛋的价格贵得离谱。
2. sbuorbital
adj.未进入（地球）轨道的，亚轨道的；在眼眶之下的 *sub(=under)
suborbital flight （宇宙飞船等的）亚轨迹飞行
3. orbit
n.（天体、宇宙飞船等的）轨道 v.进入轨道；沿轨道飞行、盘旋
the earth's orbit round the sun 地球围绕太阳的轨道
How many spacecraft have orbited the moon ? 有多少宇宙飞船绕月球运行过？
4. orbital
adj.轨道的
spacecraft's orbital distance the earth. 宇宙飞船距离地球的轨道距离
orbital velocity 轨道速度
〔李〕[orb] n.球； [诗]眼； 轨道 v.使形成球体； 包围 ←orb,orbit (L orbis,orbita)=circle 圆圈