1. （电台或电视台的）简明新闻，简短消息，简讯
A bulletin is a short news report on the radio or television.
e.g. ...the early morning news bulletin.
早间新闻简报
2. 公告；布告
A bulletin is a short official announcement made publicly to inform people about an important matter.
e.g. At 3.30 p.m. a bulletin was released announcing that the president was out of immediate danger.
下午3点30分发布了公告，称总统已经暂时脱离危险。
3. （学校、教堂等机构或团体发放的）学报，会刊，小册子
A bulletin is a regular newspaper or leaflet that is produced by an organization or group such as a school or church.
名词公告；布告；（电台或电视台的）新闻简报；（机构或组织的）简报动词告示网络公报；报告；通报