Synonyms of fantastic in English:

fantastic


See US English definition of fantastic

See UK English definition of fantastic

See Spanish definition of fantástico

adjective

1‘it's a fantastic notion, but it would explain everything’

SYNONYMS
fanciful, extravagant, extraordinary, irrational, wild, mad, absurd, far-fetched, nonsensical, incredible, unbelievable, unthinkable, implausible, improbable, unlikely, doubtful, dubious
strange, peculiar, odd, queer, weird, eccentric, insane, whimsical, capricious
imaginary, visionary, romantic, unreal, illusory, make-believe
informal crazy, cock-eyed, oddball, off the wall
British informal barmy, potty, daft
ANTONYMS

rational

2‘a memory of fantastic accuracy’

SYNONYMS
tremendous, remarkable, great, terrific, enormous, huge, striking, impressive, outstanding, phenomenal, monumental, overwhelming

3‘the mountains assumed weird and fantastic shapes’

SYNONYMS
strange, weird, bizarre, outlandish, queer, peculiar, eccentric, grotesque, freakish, surreal, exotic
whimsical, fanciful, quaint, imaginative, elaborate, ornate, intricate, rococo, baroque, phantasmagoric, Kafkaesque
ANTONYMS

ordinary, unremarkable

4‘a fantastic new car’

SYNONYMS
marvellous, wonderful, sensational, magnificent, outstanding, superb, superlative, excellent, very good, first-rate, first-class, dazzling, out of this world, breathtaking
informal great, terrific, tremendous, fabulous, fab, mega, super, stellar, ace, magic, A1, cracking, cool, wicked, awesome, amazeballs, way-out, def, supercalifragilisticexpialidocious
British informal brilliant, brill, smashing, bosting
Australian, New Zealand informal bonzer
British informal, dated spiffing, topping, tip-top, top-notch, capital
ANTONYMS

ordinary, poor