Old Faithful
/ˌəʊld ˈfeɪθfl/
/ˌəʊld ˈfeɪθfl/
- a famous US geyser (= an underground hot spring that shoots water or steam up into the air) in Yellowstone National Park. It is a popular tourist attraction. Approximately once an hour it shoots hot water and steam into the air to a height of about 150 feet/46 metres.