Possible synonyms of seriousness can be earnestness OR if seriousness means the condition of being grave and of involving serious consequences, one could use gravity. As Gee told you 2 synonyms are never completely alike and it all depends on the context too. Good luck.
To find synonyms of words you may have a look in a dictionary. On line there is - among others - http://www.rhymezone.com/ where you can enter "seriousness" and ask for synonyms. As you spoke about "beautiful translations" you should mind the subtleties, for 2 synonyms are never completely alike. If they were, you wouldn't have 2 different words.
Posts: 113
23 Nov. 2007