by 1939, arbitrary coinage, modeled on million, etc. Compare zillion, gazillion.
Entries linking to jillion
million n.
"ten hundred thousand, a thousand thousands," late 14c., milioun, from Old French million (late 13c.), from Italian millione (now milione), literally "a great thousand," augmentative of mille "thousand," from Latin mille, which is of uncertain origin. From the start often used indefinitely for "a very great number or quantity."
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 million" in Latin would have been decies centena milia, literally "ten hundred thousand." Million to one as a type of "long odds" is attested from 1761. Related: Millions.
zillion n.
by 1927, arbitrary humorous coinage with no definite numerical value; a 1922 representation of youthful exaggeration in a magazine story has billion-rillion-zillion years. OED's 1901 date from an Ohio newspaper appears to be a typo for billion. Compare jillion, gazillion.
gazillion n.
by 1984, with made-up prefix and ending from billion, trillion, etc. Perhaps based on earlier zillion.