solemn - serious
The word ‘solemn’ can be used in a few different senses, all related to the idea of something serious or dignified. It can describe a person who is sad, imparting bad news, or attending a sombre occasion, an earnest promise or vow, or something that is performed in a very sober and noble way.
The funeral was a very solemn occasion. It is always particularly tragic when a person dies so young.
When I went into business with Jane, we both made a solemn vow that we would be open and transparent in everything we did.
As soon as Mary heard the doctor begin to speak solemnly, she knew he was about to give her some bad news.
There was an absence of the appropriate solemnity at the war commemoration. It was used more for political propaganda.