noun, plural zil·lions, (as after a numeral) zil·lion.
- an extremely large, indeterminate number.
adjective
- of, relating to, or amounting to a zillion.
noun plural -lions or -lion
- (often plural) an extremely large but unspecified number, quantity, or amountzillions of flies in this camp
determiner
-
- amounting to a zilliona zillion different problems
- (as pronoun)I found a zillion under the sink
1944, arbitrary coinage with no definite numerical value; first recorded in Damon Runyon.