initial

n. 词首大写字母
a. 开始的,最初的,字首的
v. 签姓名的首字母

Please write down your initials on each page of the paper.

请在每页考卷上写下名字的首字母。

The word `hour' is pronounced without an initial aspirate.

hour一字的开头字母h不发送气音.