| Physics. a unit of permeability, representing the flow, at 1 atmosphere, of 1 cubic centimeter of fluid with 1 centipoise viscosity in 1 second through a 1-square-centimeter cross section of porous medium 1 centimeter long. |

| darcy (där'sē') Pronunciation Key
A unit used to measure the permeability of porous substances such as soil. One darcy is equal to the passage of 1 cubic centimeter of fluid having a viscosity of 1 centipoise for 1 second under the pressure of 1 atmosphere through a medium having a volume of 1 cubic centimeter. |
| Darcy, , Henry Philibert Gaspard 1803-1858.
British geologist who formulated the law (now named for him) governing the rate at which a fluid flows through a permeable medium. The darcy unit, used to measure the permeability of porous substances, is also named after him. |