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

Chronic kidney disease and high blood pressure are closely linked and, when not managed appropriately, can lead to serious outcomes such as heart attack, stroke, heart failure and progression to kidney failure.

Read more on Science Daily

She had a serious eye condition that had left permanent damage.

Read more on BBC

We also learn about the serious financial troubles her fashion business faced, and how she feared she might "lose everything".

Read more on BBC

There is a higher risk of a serious fall in US stocks than is currently being reflected in the market, the head of JP Morgan has told the BBC.

Read more on BBC

When I spoke to Farage on a visit to Aberdeen earlier this year he insisted that Reform UK was now a serious contender in Scottish politics.

Read more on BBC

Related Words

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