/'hedə(r); `hɛdɚ/
n
1 (infml 口) dive or fall (esp into water) with the head first 头部向下跳水或跌落（尤指入水）
*take a header into the swimming-pool 头先入水跳入游泳池.
2 (in football) act of hitting the ball with the head （足球运动中）用头顶球.

n[C]
an action in football in which you hit the ball with your head
information at the top of a page, especially things such as numbers that appear on each page of a document
information at the beginning of an email message that shows when it was sent, who wrote it etc
→double-header