serious

[seer-ee-uhs]

adjective

1. of, showing, or characterized by deep thought.

2. of grave or somber disposition, character, or manner.

   a serious occasion; a serious man.

   Synonyms: staid, sedate, sober

3. being in earnest; sincere; not trifling.

   His interest was serious.

   Antonyms: trifling, frivolous

4. requiring thought, concentration, or application.

   serious reading; a serious task.

5. weighty or important.

   a serious book; Marriage is a serious matter.

   Synonyms: grave, momentous
   Antonyms: trivial

6. giving cause for apprehension; critical.

   The plan has one serious flaw.

7. 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

1. that which is of importance, grave, critical, or somber.

   You have to learn to separate the serious from the frivolous.

serious

/ ˈsɪərɪəs /

adjective

1. grave in nature or disposition; thoughtful

   a serious person

2. marked by deep feeling; in earnest; sincere

   is he serious or joking?

3. concerned with important matters

   a serious conversation

4. requiring effort or concentration

   a serious book

5. giving rise to fear or anxiety; critical

   a serious illness

6. informal,  worthy of regard because of substantial quantity or quality

   serious money

   serious wine

7. informal,  extreme or remarkable

   a serious haircut

Other Word Forms

• seriousness noun
• half-serious adjective
• half-seriously adverb
• nonserious adjective
• nonseriously adverb
• overserious adjective
• overseriously adverb
• quasi-serious adjective
• quasi-seriously adverb
• superserious adjective
• superseriously adverb
• ultraserious adjective
• ultraseriously adverb
• unserious adjective
• unseriously adverb

Word History and Origins

Origin of serious¹

First recorded in 1400–50; late Middle English, from Middle French serieux and Latin sērius “grave, earnest” or Late Latin sēriōsus; -ous, -ose ¹

Word History and Origins

Origin of serious¹

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

Synonym Study

See earnest ¹.

Example Sentences

The Tripoli-based government then condemned what it called a "failed attempt" and a "serious act aimed at undermining security and stability, and damaging Libya's relations with the international community".

Read more on Barron's

“The U.S. is under serious pressure to sell agriculture to China and China isn’t budging,” she said.

Read more on Barron's

And if the report is right, it means the central bank could be making a serious mistake by slashing interest rates too fast and too soon while inflation is still elevated.

Read more on MarketWatch

These shifts pose serious risks to their survival—and to the stability of the ecosystems that depend on them.

Read more on Science Daily

On Monday, Eswatini accepted 10 deportees despite legal challenges, adding to an earlier group of five, which the US had described as serious criminals.

Read more on BBC

Related Words

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