immense
Brobdingnagian, colossal, elephantine, enormous, extensive, giant, gigantic, ginormous (informal) great, huge, humongous or humungous (U.S. slang) illimitable, immeasurable, infinite, interminable, jumbo (informal) large, mammoth, massive, mega (slang) monstrous, monumental, prodigious, stellar (informal) stupendous, titanic, tremendous, vast
Antonyms
infinitesimal, little, microscopic, minuscule, minute, puny, small, tiny