In the West it was used mainly by mathematicians until 16c., but India, with its love of large numbers, had names before 3c. for numbers well beyond a billion. The ancient Greeks had no name for a number greater than ten thousand, the Romans for none higher than a hundred thousand. "...
A googolplex is 10 raised to the power of a googol (10^googol), an unimaginably large number, while a centillion in the U.S. is 10 raised to the 303rd power (10^303), vastly smaller than a googolplex but still incredibly large.