serious
Important; weighty; not insignificant.
Word facts
Definition of Serious
Really intending what is said (or planned, etc); in earnest; not jocular or deceiving.
Example sentences
It was a surprise to see the captain, who had always seemed so serious, laugh so heartily.
This is a serious problem. We'll need our best experts.
Using Serious well
A closer look at how serious is used — meaning in plain English, how close synonyms differ, and examples at different levels.
Something important enough to be treated with care and concern, or a person who is thoughtful and not joking.
Use it when something demands real attention because it could have significant consequences, or to describe someone's earnest, no-nonsense manner. It also works informally to mean 'large in amount' (serious money).
Common in news, health and safety contexts, personal descriptions, and casual emphasis ('serious talent').
Do not confuse 'serious' (grave, important) with 'seriously' as a casual intensifier; and note that 'a serious injury' means a bad one, while 'a serious student' means a diligent, earnest one.
- grave
- more formal and heavier; suggests danger or a somber mood
- severe
- emphasizes intensity or harshness rather than importance
- earnest
- focuses on sincerity of manner, with none of the 'dangerous' meaning
- solemn
- adds a formal, ceremonial dignity, often quiet and reverent
- significant
- neutral and measured; stresses importance without implying worry
- trivial
- the opposite of important; too minor to worry about
- lighthearted
- opposite of the earnest manner; playful and easygoing
- frivolous
- carelessly unserious, often with a hint of disapproval
- minor
- small in scale or consequence, the mild opposite
- Beginner This is a serious problem, so we need to fix it now.
- In writing Her serious expression told everyone the news was not good.
- Advanced Beneath his playful tone lay a serious argument that few in the room were prepared to answer.
If you'd stop smiling to deal with it, it's probably serious.
Synonyms for Serious
Antonyms for Serious
Related words
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Words that rhyme with Serious
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FAQ
Questions people ask
What does serious mean?
Important; weighty; not insignificant. It is an adjective.
How many syllables does serious have?
There are 3 syllables in serious, divided as sih·ree·uhs when spoken.
What part of speech is serious?
In a sentence, serious functions as an adjective. As a verb, it describes an action or state.
What are synonyms for serious?
Close in meaning to serious are solemn, earnest, grievous, critical — choose the one whose tone fits your sentence.
How do you use serious in a sentence?
Example: "It was a surprise to see the captain, who had always seemed so serious, laugh so heartily."