noun plural -lions or -lion 1. (often plural) an extremely large but unspecified number, quantity, or amount ⇒ zillions of flies in this camp determiner 2.
a. amounting to a zillion ⇒ a zillion different problems
b. (as pronoun) ⇒ I found a zillion under the sink
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Word origin of 'zillion'C20: on the model of million