solemn and thoughtful; not frivolous 严肃的; 庄重的; 正经的: a serious person, mind, appearance 严肃的人﹑ 心情﹑ 外表 * Her face was serious as she told us the bad news. 她告诉我们这个坏消息时脸色很严肃. * He seems very serious, but in fact he has a delightful sense of humour. 他看上去很严肃, 其实他十分诙谐. * Please be serious for a minute, this is very important. 请严肃点儿, 这事很重要. 
[usu attrib 通常作定语] (of books, music, etc) intended to provoke thought; not merely for amusement （指书﹑ 音乐等）启发思考的, 不仅为消遣的: a serious essay about social problems 关於社会问题的发人深省的文章 * Do you ever read serious works? 你看不看理论性的着作? 
important because of possible danger or risk; grave 严重的（可能有危险或风险的）; 重大的: a serious illness, mistake, accident 严重的疾病﹑ 错误﹑ 事故 * a serious decision about giving up a steady job 要放弃一份稳定工作的重大决定 * That could cause serious injury. 那可能造成重伤. * The international situation is extremely serious. 国际形势极为严峻. 
~ (about sb/sth) in earnest; sincere 认真的; 真诚的: a serious suggestion 诚恳的建议 * Are you really serious about him? ie Do you have sincere affection for him? 你真对他有意吗? （是否真心爱他?） * Is she serious about learning to be a pilot? 她真想学开飞机吗?> seriously adv
1 in a serious way 严肃地; 庄重地; 启发性地; 严重地; 认真地: speak seriously to her about it 跟她认真地谈谈这件事 * seriously ill, injured, etc 病得﹑ 伤得...很重.
2 (infml 口) (used at the beginning of a sentence when turning to a serious matter 用以将话题转到正经事上, 置於句首): Seriously though, you could really hurt yourself doing that. 说正经的, 你那样做可真要自讨苦吃了. =>Usage at hopeful 用法见hopeful.
3 (idm 习语) take sb/sth seriously regard sb/sth as important and worth treating with respect 认真对待某人[某事物]: You can't take her promises seriously: she never keeps her word. 她答应的事不必当真, 她从来说话不算数. * I take this threat very seriously. 我认为这种威胁非同小可.
seriousness n [U] 1 state of being serious 严肃; 庄重; 严重; 认真: the seriousness of his expression 他的表情严肃 * the seriousness of the crisis 危机的严重性. 2 (idm 习语) in all `seriousness (infml 口) very seriously; not as a joke 极严肃﹑ 庄重﹑ 严重或认真; 并非玩笑: You can't in all seriousness go out in a hat like that! 你戴着那种帽子出门不是开玩笑嘛!