cavernousEnglishOxford American Thesauruscavernous adjective the cavernous cargo space: vast, huge, large, immense, spacious, roomy, airy, commodious, capacious, voluminous, ample, rambling, extensive, high, deep; hollow, gaping, yawning, unfathomable; dark, gloomy, dismal, sepulchral. ▷antonyms small, poky.