noun: (colloquial) Something important; (with 'the') the most important one, (especially sports) the big game, the big play.
noun: (US, colloquial) One hundred or one thousand dollars.
noun: (US, colloquial) A dollar.
noun: (seismology, colloquial, usually with the) A hypothetical massive earthquake somewhere along the Pacific coast of North America, but especially one projected to cause catastrophic damage to a major city such as Vancouver, Seattle, San Francisco, or Los Angeles.
noun: (colloquial, by extension) Any other hypothetical event with the potential to be far more devastating than previous events of the same type.