solemn

Adjective

• characterized by a firm and humorless belief in the validity of your opinions
  • both sides were deeply in earnest, even passionate
    
  • an entirely sincere and cruel tyrant
    
  • a film with a solemn social message
    

• dignified and somber in manner or character and committed to keeping promises
  • a grave God-fearing man
    
  • a quiet sedate nature
    
  • as sober as a judge
    
  • a solemn promise
    
  • the judge was solemn as he pronounced sentence
    

Related words

• Synonyms: 
  earnest , sincere , grave , sedate , sober