WordNet sense 1 (extraordinarily good; used especially as intensifiers):

fantastic, grand, howling, rattling, terrific, tremendous, wonderful, wondrous, marvellous

WordNet sense 2 (beyond what is ordinary or usual; highly unusual or exceptional or remarkable):

extraordinary

WordNet sense 3 (being or having the character of a miracle):

miraculous

WordNet sense 4 (not existing in nature or subject to explanation according to natural laws; not physical or material):

supernatural

WordNet sense 5 (too improbable to admit of belief):

improbable, tall

WordNet sense 6 (beyond belief or understanding):

incredible, unbelievable