most serious

ADJECTIVE

somber, humorless

Synonyms

STRONGEST

deliberate genuine honest severe sincere thoughtful

STRONG

sober

WEAK

austere bound bound and determined businesslike cold sober contemplative deadpan determined downbeat earnest funereal go for broke grave grim intent long-faced meditative no-nonsense pensive pokerfaced reflective resolute resolved sedate set solemn staid steady stern unhumorous unsmiling weighty

Antonyms

STRONGEST

deceptive dishonest false insincere misleading untrustworthy

WEAK

flippant funny happy light minor trivial unimportant unserious

ADJECTIVE

crucial, weighty

Synonyms

STRONGEST

dangerous deep difficult far-reaching grievous important major meaningful severe significant tough urgent

WEAK

arduous fateful fell formidable grave grim hard heavy laborious meaning business menacing momentous no joke no laughing matter of consequence operose out for blood playing hard ball pressing smoking sobering strenuous strictly business threatening ugly unamusing unhumorous worrying

Antonyms

STRONGEST

calm easy facile friendly insignificant little meaningless minor small trivial unimportant worthless

WEAK

flippant funny happy light unserious

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

Spanish media say the incident has been described internally by several members of staff as "the most serious ever experienced in Valdebebas".

From BBC • May 7, 2026

Dubbed the Fifth Avenue of the West and the Champs-Élysées of the Pacific, Wilshire has long been identified as L.A.’s most serious contender for heavy rail.

From Los Angeles Times • May 7, 2026

Heart attacks remain one of the most serious medical emergencies in the United States, with an estimated 785,000 new cases each year.

From Science Daily • May 5, 2026

Anyone who knows a farmer has heard stories of the “worst year ever” — but now American farmers are facing their most serious crisis since the 1980s.

From MarketWatch • May 4, 2026

That the justices have already decided he is the most important criminal, that he has committed a most serious offense.

From "The Boy Who Dared" by Susan Campbell Bartoletti