The Rice University Neologisms Database

an infinite measure; an incalculable and indeterminate number. Gazillion was derived from the 1940’s word zillion, recorded by Damon Runyon. Adolescents tend to exaggerate in their speech, whether there is a logical backing or not. By adding ga- to zillion the idea of an infinite number larger than zillion is alluded to, despite the illogical basis for such a number. The rhythmic flow of the gazillion following million may also have contributed to its common usage. Children and adolescents commonly say such phrases as “a million, kazillion, gazillion,” in order to capture this infinitely continuous number or measure. Taken from ‘zillion’ to ‘gazillion’ there is a stronger emphasize put on the beginning of the word as it becomes a voiced velar plosive, as opposed to lower voiced fricative. This transition may have also given adolescents more of a reason to use this word in exaggerating certain situations (i.e. how incredibly old something is or how bored they are). I’d also like to mention the word's usage in teenage speech, in which case it is often used for a humorous exaggeration.