来源于希腊语，意为"around,on all sides",其变形为circ,circu。此外，与circum意思相近的前缀还有ambi,peri.
circum-原来是个拉丁介词或副词，意思相当于around或about。作为一个介（副）词性质的原生词缀，它一般附在拉丁动词词干前，构成原生动词或相应的名词与形容词。在现代英语中，它也可以充当派生词缀，加在拉丁借词前，构成的往往是科技用词。 1.circlet
n.round band of gold or flowers worm as an ornament on the head,neck or arm,ring 环形饰物；戒指 *cire(=around)
例句：After the exhibition,several circlets were found to be missing from the royal jewels.展览结束以后，皇宫珠宝中的几个环形饰物不见了。

2.circuit
n.circular journey,detour;closed path for an electrical current 周游，巡回；电路，线路 *circ(=around),it (=go)
例句：Two switches had to be tumed to complete the electrical circuit.这个电路需要两个开关才能完成。

3.circulate
v.go around continuously,diffuse（使）流通，，（使）运行，（使）循环，（使）传播 （使成圆形） *circ (=around),lat(=carry)
例句：This herb is believed by the Chinese to help your blood circulate.中国人相信草药可以促进血液循环。

4.circumference
n.perimeter 圆周 （绕行） *circum (=around),fer (=carry)
例句：We learned in geometry that it is possible to caculate the circumference of a circle.学过几何后我们知道，圆的周长是可以计算出来的。

5.circumspect
adj.cautious,well-considered 慎重的，充分考虑的 （仔细向四周看看） *circum (=around),spect(=look)
例句：Since the accident,the bus company is much more circumspect about hiring inexperienced drivers.自从那次事故以后，公共汽车公司在雇用没有经验的司机时更加慎重了。