While "bajillion" is not a formally recognized word, it is used colloquially to mean an unquantifiable or extremely large number. There are many synonyms that can be used instead, such as zillions, gazillions, trillions, quadrillions, countless, copious, myriad, numerous, infinite, and immeasurable. These words all convey similar meanings to "bajillion" and can be used interchangeably to express a notion of immense quantity. While these words may not fit well in formal writing, they are perfect for light-hearted conversation and emphasize the speaker's excitement or exaggeration about a topic.