Any important situation is serious, and this word is also the opposite of humorous and playful.

If you're frowning, someone might say, "Why so serious?" This is a word for people and situations where there's no fooling around. If you're staring at the computer screen, typing quickly, you look serious. If you are in a car accident, that's a serious situation. Some people are more serious than others. If you're always making jokes and smiling, then you're not that serious. One place everyone needs to be serious is at a funeral home.

Definitions of serious
  1. adjective
    of great consequence
    “marriage is a serious matter”
    important, of import
    of great significance or value
  2. adjective
    requiring effort or concentration; complex and not easy to answer or solve
    “raised serious objections to the proposal”
    “the plan has a serious flaw”
    difficult, hard
    not easy; requiring great physical or mental effort to accomplish or comprehend or endure
  3. adjective
    completely lacking in playfulness
    synonyms: sober, unplayful
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    full of fun and high spirits
    coltish, frolicky, frolicsome, rollicking, sportive
    given to merry frolicking
    devilish, rascally, roguish
    playful in an appealingly bold way
    elfin, elfish, elvish
    usually good-naturedly mischievous
    arch, impish, implike, mischievous, pixilated, prankish, puckish, wicked
    naughtily or annoyingly playful
    frisky, kittenish
    playful like a lively kitten
    mocking, quizzical, teasing
    playfully vexing (especially by ridicule)
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  4. adjective
    appealing to the mind
    “a serious book”
    synonyms: good
    appealing to or using the intellect
  5. adjective
    concerned with work or important matters rather than play or trivialities
    “a serious student of history”
    “a serious attempt to learn to ski”
    “gave me a serious look”
    “a serious young man”
    “are you serious or joking?”
    “Don't be so serious!”
    earnest, sincere, solemn
    characterized by a firm and humorless belief in the validity of your opinions
    grave, sedate, sober, solemn
    dignified and somber in manner or character and committed to keeping promises
    excessively serious
    not to be taken lightly
    serious-minded, thoughtful
    acting with or showing thought and good sense
    tending to make sober or more serious
    of a substantial character and not frivolous or superficial
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    not serious in content or attitude or behavior
    concerned with or comprehending only what is apparent or obvious; not deep or penetrating emotionally or intellectually
    airheaded, dizzy, empty-headed, featherbrained, giddy, light-headed, lightheaded, silly
    lacking seriousness; given to frivolity
    flighty, flyaway, head-in-the-clouds, scatterbrained
    guided by whim and fancy
    flippant, light-minded
    showing inappropriate levity
    idle, light
    silly or trivial
    intended primarily as entertainment; not serious or profound
    concerned with trivialities
    show more antonyms...
  6. adjective
    causing fear or anxiety by threatening great harm
    “a serious wound”
    “a serious turn of events”
    synonyms: dangerous, grave, grievous, life-threatening, severe
    being in or verging on a state of crisis or emergency
Word Family

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