letterboxes
英 [ˈletəbɒksɪz]
美 [ˈletərbɑːksɪz]
n. 邮筒，信箱
letterbox的复数
柯林斯词典
- （门上的）信件投递孔；（建筑物入口处的）信箱
A letterbox is a rectangular hole in a door or a small box at the entrance to a building into which letters and small parcels are delivered. - （电视或计算机显示）信箱格式的，上下黑边的，宽屏的
If something is displayed on a television or computer screen in letterbox format, it is displayed across the middle of the screen with dark bands at the top and bottom of the screen.
in AM, usually use 美国英语通常用 mailbox