Darcy vs Darky - What's the difference?

As nouns the difference between darcy and darky

is that darcy is a (non si) unit of area used in measuring the permeability of porous solids such as powders while darky is .

(s)

from a place d'Arcy in Northern France.

, transferred from the surname.

of mostly American usage since the mid-twentieth century.

(darkies)