Synonyms of serious

serious

adjective

ˈsir-ē-əs 

1

as in solemn

not joking or playful in mood or manner

I'm serious when I say that no one should be walking in that neighborhood at night

Synonyms & Similar Words

• solemn
• severe
• earnest
• stern
• professional
• sober
• harsh
• humorless
• unsmiling
• distinguished
• grave
• po-faced
• staid
• sedate
• strict
• no-nonsense
• weighty
• uncomic
• sobersided
• grim
• businesslike
• dignified
• serious-minded
• gloomy
• elevated

Antonyms & Near Antonyms

• humorous
• joking
• playful
• flippant
• jocular
• facetious
• funny
• ridiculous
• light
• flip
• comical
• ludicrous
• hysterical
• comic
• hilarious
• ludic
• farcical
• laughable
• riotous
• kittenish
• uproarious
• frivolous
• antic
• risible
• droll
• jesting
• lighthearted
• goofy
• screaming
• silly
• puerile
• absurd
• foolish
• insane
• mad
• crazy
• unwise
• harebrained
• scatterbrained
• sidesplitting
• zany
• flighty
• wacky
• preposterous
• nonsensical
• nutty
• fatuous
• senseless
• asinine
• loony
• kooky
• jerky
• daft
• sappy
• light-headed
• cuckoo
• brainless
• witless
• daffy
• balmy
• featherbrained
• cockeyed
• screwball
• weak-minded
• dotty
• half-witted

2

as in important

having a matter of importance as its topic

a very serious film that dealt with the aftermath of the Gulf War

Synonyms & Similar Words

• important
• big
• major
• meaningful
• heavy
• significant
• substantial
• grave
• solid
• weighty
• momentous
• consequential
• portentous
• eventful
• material

Antonyms & Near Antonyms

• light
• small
• little
• minor
• unserious
• trivial
• slight
• silly
• frivolous
• insignificant
• unimportant
• Mickey Mouse
• lite

3

as in dangerous

involving potential loss or injury

a serious accident

Synonyms & Similar Words

• dangerous
• hazardous
• risky
• perilous
• unsafe
• precarious
• menacing
• grievous
• threatening
• grave
• treacherous
• unhealthy
• venturesome
• fatal
• random
• parlous
• uncertain
• detrimental
• jeopardizing
• adverse
• unpleasant
• destructive
• bad
• harmful
• chance
• lethal
• sickening
• deadly
• insecure
• nasty
• ugly
• haphazard
• dicey
• distressing
• injurious
• murderous
• dire
• deleterious
• pernicious
• killer
• fell
• malignant
• wicked
• ill
• evil
• hurtful
• mortal
• inimical
• ultrahazardous
• baneful
• noxious
• fateful
• baleful
• deathly
• pestilent

Antonyms & Near Antonyms

• harmless
• innocent
• safe
• innocuous
• good
• beneficial
• nonthreatening
• nonhazardous
• advantageous
• unthreatening
• ultrasafe

Synonym Chooser

How is the word serious different from other adjectives like it?

Some common synonyms of serious are earnest, grave, sedate, sober, solemn, and staid. While all these words mean "not light or frivolous," serious implies a concern for what really matters.

a serious play about social injustice

In what contexts can earnest take the place of serious?

Although the words earnest and serious have much in common, earnest suggests sincerity or often zealousness of purpose.

an earnest reformer

When would grave be a good substitute for serious?

While in some cases nearly identical to serious, grave implies both seriousness and dignity in expression or attitude.

read the proclamation in a grave voice

When is it sensible to use sedate instead of serious?

While the synonyms sedate and serious are close in meaning, sedate implies a composed and decorous seriousness.

remained sedate amid the commotion

Where would sober be a reasonable alternative to serious?

The words sober and serious are synonyms, but do differ in nuance. Specifically, sober stresses seriousness of purpose and absence of levity or frivolity.

a sober look at the state of our schools

When might solemn be a better fit than serious?

The synonyms solemn and serious are sometimes interchangeable, but solemn suggests an impressive gravity utterly free from levity.

a sad and solemn occasion

When is staid a more appropriate choice than serious?

In some situations, the words staid and serious are roughly equivalent. However, staid suggests a settled, accustomed sedateness and prim self-restraint.

a quiet and staid community

Example Sentences

Recent Examples of serious

In her second trial she was found not guilty of the most serious charges, including second-degree murder, manslaughter and leaving the scene after an accident resulting in death. —Nadine El-Bawab, ABC News, 4 June 2026

Mercury — now in Cancer and your eighth house of joint ventures and psychological motivations — will clash with Saturn, which could trigger serious conversations around dating, children or even financial entanglements. —Valerie Mesa, PEOPLE, 4 June 2026

My guess is that some users are looking at government posts to X as serious statements of policy. —Drew Pittock, USA Today, 4 June 2026

The victim was shot in the stomach and taken to the University of Chicago Medical Center in serious condition. —Elyssa Kaufman, CBS News, 4 June 2026