1. The trait of being serious
   "a lack of solemnity is not necessarily a lack of seriousness";
   - earnestness, serious-mindedness, sincerity
    
2. An earnest and sincere feeling
   "The seriousness of her tone conveyed the gravity of the situation";
   - earnestness, sincerity
    
3. The quality of arousing fear or distress
   "he learned the seriousness of his illness";
   - distressfulness

See also: frivolous, serious

Type of: badness, gravity, severeness [rare], severity, solemness, solemnity, solemnness, trait

Encyclopedia: Seriousness