solemn

adjective5

1. •
   Deeply serious and sombre; grave.
2. •
   Characterized by or performed with appropriate or great ceremony or formality.
3. •
   Inspiring serious feelings or thoughts; sombrely impressive.
4. •
   Of or pertaining to religious ceremonies and rites; (generally) religious in nature; sacred.
5. •
   (no longer used) Cheerless, gloomy, sombre.