What does borehole mean?
A borehole is a narrow, deep hole drilled into the ground or rock, most often to reach water, but also used for extracting oil and gas, taking geological samples, or installing instruments that monitor underground conditions. Unlike a traditional well — which may be a wider shaft dug by hand or machine — a borehole is characteristically produced by mechanical drilling rigs and is typically much narrower than it is deep. The term is standard vocabulary in hydrology, civil engineering, mining, and environmental science, and it appears frequently in discussions of groundwater supply, especially where communities depend on drilled wells rather than piped municipal systems. Boreholes can range from shallow holes a few metres deep to extraordinary feats of engineering extending many kilometres into the Earth's crust for scientific study. The word is neutral and technical in tone, used comfortably in formal reports and everyday speech alike wherever drilled wells are discussed.
nounA deep, narrow hole drilled into the ground, typically to obtain water, oil, gas, or geological samples.
- A narrow hole drilled into the ground or rock to extract water, oil, gas, or minerals, or to investigate subsurface conditions.
- In engineering and geology more broadly: any exploratory or monitoring hole made by drilling equipment.
"The village's new borehole finally supplied clean water to every household."
"Engineers sank a borehole two hundred metres deep to reach the aquifer beneath the farm."
"Core samples taken from the Antarctic borehole revealed climate data spanning thousands of years."
Standard regular plural; commonly used when describing networks of wells or multiple sampling sites.
"Several boreholes were sunk across the site to map the extent of the aquifer."
Some of the deepest boreholes on Earth go down over 12 kilometres — deeper than the Mariana Trench is deep — yet they're only about as wide as a dinner plate.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of borehole
The word borehole is a straightforward compound of "bore," from the Old English verb borian meaning "to pierce or drill," combined with "hole," from Old English hol. Both elements are Germanic in origin, with "bore" related to cognates in other Germanic languages such as Old Norse bora. The compound arose in English during the industrial era, when mechanized drilling made deep narrow holes a distinct category from dug wells; it has been in use since at least the early nineteenth century. Its components remain fully transparent, so it functions as a self-explaining technical term.
How borehole is actually used
"Borehole" is standard in British English and common in technical, hydrological, and mining contexts in both varieties; American English more often uses "well" for water sources, reserving "borehole" mainly for scientific and engineering usage. The word carries no strong connotation — it is neutral and technical in register.
Easily confused with borehole
A well is traditionally a shaft dug or sunk for water (often wide and lined), while a borehole is specifically a narrow hole made by mechanical drilling.