Wikipedia
Eithne is a female personal name of Irish origin. The meaning is "kernel or grain".
Other spellings and earlier forms include Ethnea, Ethlend, Ethnen, Ethlenn, Ethnenn, Eithene, Ethne, Aithne, Enya, Ena, Edna, Etney, Eithnenn, Eithlenn, Eithna, Ethni, Edlend, Edlenn.
Eithne is considered by some sources to be the feminine cognate of the name Aidan.
The name is popular in Ireland, and is borne by a variety of historical and legendary figures.
The work Eithne, also known as Éan an Cheoil Bhinn (The Bird of Sweet Music), is considered by many critics to be the first full-scale opera written and performed in the Irish language. It was written by English/Irish composer Robert O'Dwyer.
The work saw its first performance at the Rotunda in Dublin during the Oireachtas na Gaeilge, a festival of Irish culture, in 1909.
The opera, based on a Gaeilge libretto written by Galway Reverend Thomas O'Kelly, covers three acts and includes in its complex plot the presence of stepbrothers, a divine descent to earth and the transformation of a queen into a bird.