Dictionary.com
Thesaurus.com
Synonyms

serious

American  
[seer-ee-uhs] / ˈsɪər i əs /

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 British  
/ 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

"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

Related Words

See earnest 1.

Other Word Forms

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

Etymology

Origin of serious

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

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.

Shift work disorder is linked to a range of serious concerns, including reduced mental sharpness, lower productivity, increased risk of car accidents, and more workplace injuries.

From Science Daily

“When someone sets fires that endanger lives and destroy a community’s sense of safety, my office will pursue the most serious charges available and seek justice for the victims,” Los Angeles County Dist.

From Los Angeles Times

Derbyshire Police said four men and three women, aged between 36 and 52, suffered serious but non life-threatening injuries during the incident.

From BBC

Over time, this can damage blood vessels and significantly raise the risk of heart attacks, strokes, and other serious conditions.

From Science Daily

The victims of the incident - four men and three women aged between 36 and 52 - all suffered serious but non life-threatening injuries during the incident.

From BBC