Umpteen
Umpteen is a slang term for an unspecified but somewhat large number, generally used in a humorous fashion or to imply that it is not worth the effort to pin down the actual figure. Usually it refers to the number of times something has happened, rather than a number of objects.Despite the -teen ending, which would seem to indicate that it lies between 12 and 20, umpteen is often assumed to be much larger than this - if it could ever be pinned down. It is unclear where the ump portion of the word came from, but one theory is that it could have arisen from a sound used by speakers to indicate uncertainty. A derived term using the same root is umpty-ump.
A number of other slang terms exist to connote even larger, but equally uncertain, numbers. Most are constructed by placing a nonsense syllable before the suffix -illion - e.g., gazillion.
Zillion and gazillion are fictitious very large numbers, often used to indicate that the figure being cited is uncertain but big. The terms 'a (ga)zillion' and '(ga)zillions' are used informally, meaning very many, as in the Zillions of Games software product.