Zillions is a colloquial term that describes an indefinite, vast or enormous quantity of something. When describing a quantity, especially in a casual or expressive manner, there are numerous synonyms for zillions, such as ample, infinite, incalculable, countless, tremendous, uncountable, extensive, numerous, multitudinous, and copious. These words are often used interchangeably to paint an impression of large or excessive numbers. Some other informal synonyms for zillions include bunches, loads, oodles, gazillions, billions, tons, heaps, and scads. While these words may express the same meaning as zillions, they are often used to add emphasis, passion or humor to the conversation, depending on the context.