1. 严肃的;庄严的 Someone or something that is solemn is very serious rather than cheerful or humorous.
e.g. His solemn little face broke into smiles... 他严肃的小脸蛋上突然绽放出笑容。 e.g. He looked solemn. 他看上去很严肃。
形容词frivolous