核心畫面
At the centre is the opposite of joking or playing around: this is for real, it carries weight, treat it with full attention. From that one feeling the word fans out in two directions — toward things that are weighty/important (a serious problem, a serious decision) and toward people who are earnest and not laughing (a serious person, serious about you), plus a casual modern use where 'serious' just means 'a striking amount / really impressive'.
可以想成：核心比較像「不是在開玩笑、不是在玩」——這是來真的，有份量，要用全副心神對待。從這一個感覺，字往兩個方向展…更多收起
可以想成：核心比較像「不是在開玩笑、不是在玩」——這是來真的，有份量，要用全副心神對待。從這一個感覺，字往兩個方向展開：一邊指事情本身有份量、很重要（嚴重的問題、重大的決定）；一邊指人很認真、不嬉笑（穩重的人、對你是認真的）。另外口語裡還岔出一支，純粹表示「數量大得驚人／厲害得不得了」。原始詞典資料5 筆記錄
以下是外部詞典記錄的用法，原文照列，我們還沒有寫成教學內容。上面的說明才是我們自己寫的；有些用法可能上面已經講過了。
seriousadj/ˈsɪə̯.ɹi.əs/
- 1
Without humor or expression of happiness; grave in manner or disposition.
- deadly serious
- It was a surprise to see the captain, who had always seemed so serious, laugh so heartily.
- 2
Important; weighty; not insignificant.
- This is a serious problem. We'll need our best experts.
- 3
Really intending what is said (or planned, etc); in earnest; not jocular or deceiving.
- After all these years, we're finally getting serious attention.
- He says he wants to buy the team, but is he serious?
- 4
Committed.
seriousadv/ˈsɪə̯.ɹi.əs/
- 1
dialectalseriously, in a serious manner (most often heard in take or mean serious)
- The only time I walk out on singin' is when there's muckin' about and youse don't take it serious.
資料來源：英文維基詞典 English Wiktionary（CC BY-SA 4.0）。 原文照列，未經改寫。