serious

[ seer-ee-uhs ]

/ ˈsɪər i əs /

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See synonyms for: serious / seriousness on Thesaurus.com

adjective

of, showing, or characterized by deep thought.

of grave or somber disposition, character, or manner: a serious occasion; a serious man.

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 serious matter.

giving cause for apprehension; critical: The plan has one serious flaw.

Medicine/Medical. (of a patient's condition) having unstable or otherwise abnormal vital signs and other unfavorable indicators, as loss of appetite and poor mobility: patient is acutely ill.

noun

that which is of importance, grave, critical, or somber: You have to learn to separate the serious from the frivolous.

OTHER WORDS FOR serious

2 sober, sedate, staid.

5 momentous, grave.

See synonyms for serious on Thesaurus.com

OPPOSITES FOR serious

3 frivolous, trifling.

5 trivial.

See antonyms for serious on Thesaurus.com

QUIZ

CAN YOU ANSWER THESE COMMON GRAMMAR DEBATES?

There are grammar debates that never die; and the ones highlighted in the questions in this quiz are sure to rile everyone up once again. Do you know how to answer the questions that cause some of the greatest grammar debates?

Question 1 of 7

Which sentence is correct?

His boss, whom he admires, is waiting to meet with him about the big project.

His boss, who he admires, is waiting to meet with him about the big project.

TAKE THE QUIZ TO FIND OUT

Origin of serious

First recorded in 1400–50; late Middle English, from Middle French serieux and Latin sērius “grave, earnest” or Late Latin sēriōsus; see -ous, -ose¹

synonym study for serious

3. See earnest¹.

OTHER WORDS FROM serious

se·ri·ous·ness, nounhalf-se·ri·ous, adjectivehalf-se·ri·ous·ly, adverbnon·se·ri·ous, adjective

non·se·ri·ous·ly, adverbo·ver·se·ri·ous, adjectiveo·ver·se·ri·ous·ly, adverbqua·si-se·ri·ous, adjectivequa·si-se·ri·ous·ly, adverbsu·per·se·ri·ous, adjectivesu·per·se·ri·ous·ly, adverbul·tra·se·ri·ous, adjectiveul·tra·se·ri·ous·ly, adverbun·se·ri·ous, adjectiveun·se·ri·ous·ly, adverb

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use serious in a sentence

“Benghazi was the definition of an intelligence failure,” Paul begins, dismissing the entire committee report as unserious.
Rand Paul Won’t Let Benghazi Die|Olivia Nuzzi|December 2, 2014|DAILY BEAST
But upon the appointment of Klein to that role, he criticized the choice as “political” and unserious.
Ron Klain Will Be the Best Ebola Czar Yet|Tim Mak, Abby Haglage|October 17, 2014|DAILY BEAST
The Texas Republican practically bilked his donors by running the most unserious campaign in recent American history.
Good Riddance to Steve Stockman, the Grifter Congressman Who Ran for Senate|Ben Jacobs|March 4, 2014|DAILY BEAST
The inmates of FX consider Viva to be effete, soft and unserious.
My Week At An Austrian Fat Camp|Owen Matthews|October 27, 2013|DAILY BEAST

It does, however, stand as one more sign of how unserious Congress has become about governing.
Washington’s Silly Plan to Create a National Nurse|Michelle Cottle|February 10, 2013|DAILY BEAST
He made an amusing and not altogether unserious reference to the American habit of exploding enthusiasm in dangerous fireworks.
Mark Twain, A Biography, 1835-1910, Complete|Albert Bigelow Paine
Once she began as if they were wholly serious, and once again as if they had been wholly unserious.
The Boss of Little Arcady|Harry Leon Wilson
A lot of the girls have been sick a little with colds and small and unserious diseases in the past year.
Mary Cary|Kate Langley Bosher
Still, we were both born as we are, and I've just as much right to be unserious as you have to be serious.
The Matador of the Five Towns and Other Stories|Arnold Bennett
His own father was an unscrupulous, unserious man, that was true, but at any rate he had given his son a human chance.
The Sins of the Children|Cosmo Hamilton

British Dictionary definitions for serious

serious

/ (ˈsɪərɪəs) /

adjective

grave in nature or disposition; thoughtfula serious person

marked by deep feeling; in earnest; sincereis he serious or joking?

concerned with important mattersa serious conversation

requiring effort or concentrationa serious book

giving rise to fear or anxiety; criticala serious illness

informal worthy of regard because of substantial quantity or qualityserious money; serious wine

informal extreme or remarkablea serious haircut

Derived forms of serious

seriousness, noun

Word Origin for serious

C15: from Late Latin sēriōsus, from Latin sērius; probably related to Old English swǣr gloomy, Gothic swers esteemed

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

serious

OTHER WORDS FOR serious

OPPOSITES FOR serious

Origin of serious

synonym study for serious

OTHER WORDS FROM serious

Words related to serious

How to use serious in a sentence

British Dictionary definitions for serious

Derived forms of serious

Word Origin for serious