fantastic
1 comical, eccentric, exotic, fanciful, freakish, grotesque, imaginative, odd, oddball (informal) off-the-wall (slang) outlandish, outré, peculiar, phantasmagorical, quaint, queer, rococo, strange, unreal, weird, whimsical, zany
2 ambitious, chimerical, extravagant, far-fetched, grandiose, illusory, ludicrous, ridiculous, unrealistic, visionary, wild
3 absurd, capricious, cock-and-bull (informal) implausible, incredible, irrational, mad, preposterous, unlikely
4 (informal) enormous, extreme, great, overwhelming, severe, tremendous
5 (informal) awesome (slang) bitchin' (U.S. slang) boffo (slang) brill (informal) chillin' (U.S. slang) cracking (Brit. informal) crucial (slang) def (slang) dope (slang) excellent, first-rate, jim-dandy (slang) marvellous, mean (slang) mega (slang) out of this world (informal) sensational (informal) sovereign, superb, the dog's bollocks (taboo slang) topping (Brit. slang) wonderful, world-class, common, credible, everyday, moderate, normal, ordinary, poor, rational, realistic, sensible, typical