Old Faithful Output is a geyser located in Yellowstone National Park, Wyoming, United States. It is one of the most famous geysers in the world and is known for its predictable eruptions, which occur every 44 to 125 minutes. The crossword solution for Old Faithful Output is STEAM, which is an acronym for 'STEAM, Thermal, Energy, Air, and Moisture'. This acronym is used to describe the geyser's output, which is a combination of STEAM, thermal energy, air, and moisture.