pinhead
noun [ C ] uk/ˈpɪn.hed/ us/ˈpɪn.hed/
(OF PIN)
（大头针等的）针头，钉头
the very small round end of a pin
The problem was caused by a hole no larger than a pinhead. 故障是由大头针大小的一个洞引起的。
(PERSON)
informal傻瓜，笨蛋
a stupid person