Synonyms of vast

1 Syllable

huge, broad, great, big, giant

2 Syllables

deep-set, bigger, huger, chasmal, big-deal, moby, widest, monstrous, far-flung, sweeping, king-size, hugest, mondo, outspread, greatest, massy, mammoth, fluctuant, whaling, boundless, endless, massiest, biggest, spacious, broadest, spread-out, gaping, wider, cosmic, massier, whaler, broader, scopic, buller, full-out, untold, ample, zillion

3 Syllables

chambered, bottomless, whole-hog, enormous, gigantic, thorough-going, abysmal, prodigious, stupendous, colossal, far-ranging, substantial, overdrawn, socketed, expanded, pythonic, detailed, cavernous, ginormous, limitless, grandiose, sizeable, widespread, uncrowded, gargantuan, stretched-out, titanic, immense, massive, tremendous, eternal, prolonged, humungous, cyclopean, unbounded, capacious, far-reaching, walloping, forever, leviathan, unfixed

4 Syllables

unlimited, voluminous, expandable, dilatable, distensible, astronomic, behemothic, monolithic, cosmogonic, never-ending, uncountable, extensive, larger-than-life, overwhelming, monumental, super-duper, bunyanesque, gigantesque, mastodonic, undefined, measureless, large-scale, unfathomed, cosmogonal, all-embracing, infinite

5 Syllables

supertemporal, high-falutin', encyclopedic, comprehensive, super-colossal, incomputable, unreckonable, unnumberable, uncalculable, unexclusive, immeasurable, incalculable, illimitable, astronomical, all-inclusive