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.

"But we are not able to treat the most serious injuries, for example when more than 50 percent of the body is burnt," Boucari Hamadoum said.

From Barron's • Jun. 25, 2026

The life sentence marks the most serious challenge yet to her activism.

From BBC • Jun. 24, 2026

For many, care arrived too late to prevent one of the disease’s most serious complications: amputation.

From Los Angeles Times • Jun. 14, 2026

New research in mice suggests that gut microbes and the compounds they produce may play a surprising role in protecting against some of the condition's most serious consequences, including heart disease.

From Science Daily • Jun. 9, 2026

“I am the most serious you could seriously be!”

From "A Rover's Story" by Jasmine Warga