正如名词后缀-er 一样，-or 也是最重要的表示行为者的名词后缀。不过，-or 是来源于拉丁语的非能产型的后缀。它只与拉丁语源的动词或动词词根相结合，构成名词，其意思为a person or thing that ～s（...者，...物）。由于受拉丁构词的影响，有时-or 前还带有其他拉丁词尾成份，常见的形态有-ator,-itor等，可将它们看作-or 的异体。

后缀-or 表示“人”。

1.actor [act v.表演；-or →]
n.演员
举例：The boy dreamed of becoming an actor. 那男孩子一心想当演员。

2.doctor [doct = to teach 教；-or →“教育者”→]
n.学者，先生；医生
举例：A doctor must have a license to practise medicine. 医生要有执照才能行医。

3.testator
n.man who has made a testament立遗嘱的人 test=witness
The wording of his will makes it very clear that it was the intention of the testator to leave his entire estate to his daughter.
遗嘱中的字句清楚地表明，立遗嘱的人要把全部财产都留给他的女儿。


后缀-or 表示“物”。

1.tractor 拖拉机，螺旋桨飞机
The tractor took up the slack and pulled the trailer out of the mud.
拖拉机拉紧拖缆把拖车从泥中拉了出来。

2.detector n. 探测器
A device for converting energy form one form to another. In relation to computers, the term is applied to a read/write head, to detector of sector marks in a magnetic disc system, and to electronic/sonic
pulse converters of delay line memory.

把能量从一种形式转换成另一种形式的装置。在与计算机有关时，这个术语用在磁盘系统中的读／写磁头、扇面标记的检测上，以及用在延迟线存储器的电子或声波脉冲变换器上。

3.refrigerator
n.冷藏库，冰箱
举例：Milk,meat and fish must be stored in a refrigerator to prevent spoiling. 牛奶、鱼，肉等应存放在冰箱里保鲜。