Dubh Essa (also spelled Dub Essa, Dubhessa, Dubhesa, Dubheasa, Dubh Easa, Duibhessa, Duibheasa) was a medieval Gaelic feminine given name, fairly common in 13th- and 14th-century Ireland.
[1] While the name may be a compound of Gaelic dubh "dark" (probably referring to hair color, hence "black-haired") and eas "waterfall, cascade, rapid" (genitive easa), its meaning is sometimes interpreted as "black nurse" (Latin: nutrix nigra).
[2] Dubh Essa has also been anglicized as Duvessa (e.g., in M. J. Molloy's 1964 comedy The Wooing of Duvessa).