1. a deep narrow hole made in the ground by drilling, especially to find water or oil

Examples

• The geologists drilled a borehole to test for underground water.
• Oil was discovered in the new borehole after drilling 2,000 feet down.
• Scientists lowered instruments into the borehole to measure temperature.
• The water company dug several boreholes to supply the village.
• Core samples were extracted from the borehole for analysis.
• The borehole reached a depth of 500 meters before hitting bedrock.