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A geyser in Yellowstone National Park in northwest Wyoming.
the best known geyser in Yellowstone National Park.
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|Noun||1.||Old Faithful - a geyser in Yellowstone National Park that erupts for about 4 minutes about every 65 minutes|
Yellowstone National Park - the first national park in the United States; located in the border area between Wyoming and Montana and Idaho; spectacular wilderness; famous for Old Faithful geyser and for buffalo and bears