Did you know?

Click any word in a definition or example to find the entry for that word

serious

 - definition
 
 
 
Close

What are red words?

90% of the time, speakers of English use just 7,500 words in speech and writing. These words appear in red, and are graded with stars. One-star words are frequent, two-star words are more frequent, and three-star words are the most frequent.

Close

Thesaurus

The thesaurus of synonyms and related words is fully integrated into the dictionary entries. Click on the T button in an entry to review the synonyms and related words for that meaning.

more
adjective serious pronunciation in American English /ˈsɪriəs/
  1. 1
    bad or dangerous enough to make you worried
    a serious illness/accident/injury:

    a serious head injury

    a serious problem/mistake:

    It's not a serious problem – we should be able to fix it easily.

    a serious crime/offense/threat:

    An accident like this poses a serious threat to the environment.

    The sale of the company will have serious implications for people's jobs.

  2. 2
    important and deserving attention

    This is an extremely serious matter.

    He has no serious competition for the job.

  3. 3
    meaning what you say or do, and not making a joke

    I'm sorry, I didn't realize you were being serious.

    The police have made no serious attempt to address these issues.

    serious about:

    I'm not convinced they're serious about the deal.

    serious about (doing) something:

    Do you think Mike's serious about going to live in New York?

    deadly/dead (=completely) serious:

    "Are you serious about leaving your job?" "Dead serious."

  4. 4
    careful and detailed
    serious consideration/thought/discussion:

    We'll have to give the situation some serious thought.

  5. 5
    someone who is serious thinks carefully about things and does not laugh much

    Peter seems serious but he actually has a good sense of humor.

    1. a.
      appearing worried or upset

      Is Mary all right? She looked a little serious.

  6. 7
    if you are in a serious romantic relationship with someone, you intend to stay together for a long time

    Is it getting serious with you and June?

    a serious boyfriend/girlfriend/relationship:

    He's never had a serious relationship with anyone.

  7. 9
    informal extreme, or large in amount

    We did some serious hiking last weekend.

    It's time you made some serious money.

phrases

derived word

seriousness

 serious pronunciation in American English  noun [uncountable]

pre-roll

a video advertisement that appears immediately before an online video

BuzzWord Article

Open Dictionary

breakfast rave

a rave … that takes place early in the morning and where there is no alcohol or drugs …

add a word

Blog

A must for anyone with an interest in the changing face of language. The Macmillan Dictionary blog explores English as it is spoken around the world today.

global English and language change from our blog