1 bad or dangerous 严重的；危险的: a serious accident/illness/offence 严重的意外╱疾病╱罪行Pollution is a very serious problem. 污染是很严重的问题。Her condition is serious and she's likely to be in hospital for some time. 她病得很重，可能要在医院里待一些时候。

2 needing to be treated as important, not just for fun 严肃的；认真的: Don't laugh, it's a serious matter. 不要笑，这是严肃的事情。a serious discussion 认真的讨论

3 serious (about sth/about doing sth) (used about a person) not joking; thinking about things in a careful and sensible way （指人）正经的，严肃的: Are you serious about starting your own business (= are you really going to do it)? 你真的要创立自己的生意吗？He's terribly serious. I don't think I've ever seen him laugh. 他严肃极了，我从来没有见过他笑。You're looking very serious. Was it bad news? 你看来满怀心事，是不是有什么坏消息？ ➔seriousness noun [U]