Thesaurus.com
Dictionary.com
Showing results for serious.
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.

Det Supt Oliver Little, from City of London Police, said courier fraud represented "serious organised crime" that was "very sophisticated at getting people's confidence".

From BBC • Apr. 18, 2026

In Anaheim, however, two deals that would have anchored the Angels there for decades collapsed, and the 60-year-old stadium is in serious need of renovation or replacement.

From Los Angeles Times • Apr. 17, 2026

A better approach would address the serious flaws of both TSA’s governance and the SPP’s design.

From The Wall Street Journal • Apr. 17, 2026

Don’t miss: How the ‘TACO’ trade went from a lighthearted Wall Street joke to a serious moneymaker.

From MarketWatch • Apr. 17, 2026

"Sam," Anastasia said in a serious voice, "I have something very important to tell you. Horrible, awful news. You're going to hate it just as much as I do."

From "All About Sam" by Lois Lowry

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!