letterbox

投信口、信件投递口英式

She pushed the thick envelope through the letterbox and walked away.

她把那个厚厚的信封塞进门上的投信口后就走了。

信箱、邮筒英式

There were three bills waiting in the letterbox this morning.

今天早上信箱里有三张帐单。

宽萤幕模式、上下加黑边的画面影视

The old film is shown in letterbox to keep the original framing.

这部老片以上下加黑边的方式播出，以保留原本的构图。

投递传单、发送宣传品英式

Volunteers letterboxed the whole neighborhood before the election.

选举前志工在整个社区挨家挨户投递传单。

宽扁形的、横长形的多用于名词前

The new phone has a letterbox screen for watching movies.

这支新手机采用宽扁形的萤幕，很适合看电影。