Somber is used to describe situations, facial expressions, or moods that are dark, gloomy, or depressing. Funerals are usually somber affairs.
Somber is a slightly formal word. If you have bad or super important news, deliver it in a somber manner otherwise people won’t understand how serious you are. Bad news can put a person in a somber mood. The word somber is derived from the Latin sub umbrā, "under a shadow," and it can also describe dull colors, like brown, grey, or black.