Thesaurus

Synonyms for Monumental include:

ample, astronomic, astronomical, banging, bear-sized, big, bigger, biggish, blown-up, bouffant, broad, Brobdingnagian, bulky, capacious, colossal, construction, cosmic, deep, double, earthshaking, elephantine, enlarged, enormous, epic, epoch-making, epochal, evidential, evidentiary, extended, extensive, full-size, fundamental, galactic, gargantuan, giant, gigantic, grand, great, heroic, huge, hulking, hulky, humongous, immense, important, jumbo, key, king-size, king-sized, large, large-mouthed, large-scale, larger, larger-than-life, largish, life-size, life-sized, lifesize, macro, mammoth, man-sized, massive, meaningful, medium-large, momentous, monolithic, monstrous, monumental, mountainous, noteworthy, of import, operative, outsize, outsized, overlarge, oversize, oversized, plumping, portentous, probative, probatory, prodigious, profound, puffy, queen-size, queen-sized, rangy, remarkable, significant, sizable, sizeable, spacious, structure, stupendous, super, thumping, titanic, too large, tremendous, vast, volumed, voluminous, walloping, whacking, whopping, wide, wide-ranging, world-shaking, world-shattering

monumental is a ADJ.