serious, grave, solemn, sedate, staid, sober, earnest mean not light or frivolous. serious implies a concern for what really matters.

Please don't laugh - I'm being serious. He was wearing a very serious expression and I knew something was wrong. On the surface it's a very funny novel but it does have a more serious underlying theme.

SERIOUS definition: of, showing, or characterized by deep thought. See examples of serious used in a sentence.

Define serious. serious synonyms, serious pronunciation, serious translation, English dictionary definition of serious. adj. 1. Thoughtful, somber, or grave in manner: He became serious when he …

being in earnest; sincere; not trifling: His interest was serious. requiring thought, concentration, or application: serious reading; a serious task. weighty or important: a serious book; Marriage is a …

These adjectives refer to manner, appearance, disposition, or acts marked by absorption in thought, pressing concerns, or significant work. Serious implies a concern with responsibility and work as …

Dec 17, 2025 · seriously (comparative more seriously, superlative most seriously) (manner) In a serious or literal manner. quotations

Definition of serious adjective in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

If someone is serious about something, they are sincere about what they are saying, doing, or intending to do.

Any important situation is serious, and this word is also the opposite of humorous and playful.