在以下列表中添加十个有趣的单词，并为每个单词提供简要定义。
“ethereal”，“mellifluous”，“effervescent”，“supercilious”，“nefarious”，“ebullient”，“panacea”，“serendipity”，“idiosyncrasy”，“surreptitious”
1. Ethereal: extremely delicate and light, with a heavenly or spiritual quality.
2. Mellifluous: having a smooth and pleasant-sounding flowing quality.
3. Effervescent: sparkling, lively, and full of high spirits.
4. Supercilious: behaving or looking as though one is superior to others.
5. Nefarious: wicked or criminal behavior or activities.
6. Ebullient: cheerful and full of energy.
7. Panacea: a solution or remedy for all problems or difficulties.
8. Serendipity: the occurrence of events by chance in a happy or beneficial way.
9. Idiosyncrasy: a peculiar or unique behavior or characteristic of someone or something.
10. Surreptitious: kept secret, especially because it is inappropriate or illicit.