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Definitions

serious

[seer-ee-uhs] / ˈsɪər i əs /
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.

"I am told by the doctor that we are not infectious," the captain says in the footage -- little realising the ship's British doctor would himself be in serious condition weeks later.

From Barron's • May 6, 2026

The judge said Tate's lawyers had "not persuaded me that there is a real risk of serious prejudice" and that "any trial of these criminal allegations will be many years in the future".

From BBC • May 6, 2026

The ruling requires judges to consider conditions of release — drug treatment, check-ins, social services referrals, in serious cases ankle monitoring — before resorting to money bail or detention.

From Los Angeles Times • May 6, 2026

For the average reader who wants to build serious wealth, how can they actually make it?

From MarketWatch • May 6, 2026

In his first days at home, Elisha found himself lionized in the papers as an American superhero, and in a serious fight with his family.

From "American Spirits" by Barb Rosenstock

Vocabulary lists containing serious

The SAT: Words to Capture Tone, List 3

Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!

The SAT: Multiple-Meaning Words, List 5

Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!

The New SAT: Words to Capture Tone

Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!