1N-COUNT 公告栏；布告牌 A bulletin board is a board which is usually attached to a wall in order to display notices giving information about something. 公告栏；布告牌 [mainly US]
in BRIT, use 英国英语用 noticeboard
2N-COUNT 电子布告栏；电子公告系统 In computing, a bulletin board is a system that enables users to send and receive messages of general interest. 电子布告栏；电子公告系统 [computing]
The Internet is the largest computer bulletin board in the world.