一根头发英语怎么说?

一根头发在英语中被称为 "a strand of hair"。

来源：strand 这个词本意是绳索、链条之类的细长物体，在指头发时引申为一组细长的毛发。

例句：

She picked a strand of hair out of her mouth.
她把一根头发从嘴里挑出来。
He ran his fingers through his hair, smoothing down a stray strand.
他用手指梳理头发，把一根散乱的头发放平。
The wind blew a strand of hair across her face.
风吹起一根头发飘过她的脸。