The doctor had to amputate his right leg to prevent the infection from spreading.

amputate 是动词，来自拉丁语 amputare（"切掉"）。由前缀 am-（表示"周围"）和 putare（"修剪"）组成，字面意思是"环切"。在现代医学中特指"截肢"，即通过手术切除肢体或身体部位。