| Sambahsa-mundialect | art-288 |
| serieus | |
| Lingwa de Planeta | art-287 | seriose |
| Deutsch | deu-000 | ernst |
| English | eng-000 | earnest |
| English | eng-000 | grave |
| English | eng-000 | serious |
| Esperanto | epo-000 | serioza |
| français | fra-000 | sérieux |
| Nederlands | nld-000 | ernstig |
| Nederlands | nld-000 | serieus |
| Novial | nov-000 | seriosi |
| русский | rus-000 | серьёзный |
| español | spa-000 | serio |