What is a word that mean the opposite of serious?

Antonyms for the Word serious:

1. Lighthearted
2. Halfhearted
3. Scatterbrain
4. Trivial
5. Superficial
6. Negligible
7. Insincere
8. False
9. Dishonest
10. Deceptive
11. Unserious
12. Unimportant
13. Flippant
14. Light
15. Minor