Synonyms of serious in English:

serious


See definition of serious

adjective

1‘he had a serious expression on his face’

SYNONYMS
solemn, earnest, grave, sober, sombre, unsmiling, poker-faced, stern, grim, dour, humourless, stony-faced
thoughtful, preoccupied, deep in thought, pensive, meditative, ruminative, contemplative, introspective
staid, sedate, studious, bookish
ANTONYMS

light-hearted, cheerful, jovial

2‘we have some serious decisions to make’

SYNONYMS
important, significant, consequential, of consequence, momentous, of moment, key, grave, weighty, far-reaching, major
urgent, pressing, crucial, critical, vital, life-and-death, high-priority
no joke, no laughing matter
ANTONYMS

trivial, unimportant

3‘the president should give serious consideration to this advice’

SYNONYMS
careful, detailed, in-depth, deep, profound, meaningful
ANTONYMS

superficial

4‘a serious play about Art and Life’

SYNONYMS
intellectual, highbrow, heavyweight, deep, profound, literary, learned, scholarly, cultured
classical
informal heavy
ANTONYMS

light, lowbrow, populist

5‘four of the victims received serious injuries’

SYNONYMS
severe, grave, bad, critical, acute, alarming, worrying, grievous, dreadful, terrible, dire, extreme, dangerous, perilous, precarious
archaic, humorous parlous
ANTONYMS

minor, negligible

6‘is the government serious about developing decent employment opportunities for women?’

SYNONYMS
in earnest, earnest, sincere, wholehearted, genuine, meaning what one says
committed, firm, resolute, resolved, determined
ANTONYMS

uncommitted, half-hearted, flippant

7‘she spends serious sums of money’

SYNONYMS
considerable, sizeable, substantial, appreciable, significant
goodly, tolerable, fair, reasonable, tidy, hefty, handsome, comfortable, decent, worthwhile, worth having, worth taking into account
ample, plentiful, abundant, superabundant, great, large, lavish, profuse, generous
marked, noticeable
informal not to be sneezed at, OK
literary plenteous
ANTONYMS

paltry, trifling