The name Etain is a girl's name of Irish origin meaning "jealousy". Etain and is often added to lists like Mythological Baby Names for Girls and discussed in our forums with posts like "follow the last letter".
From the experts:
The Etain of Irish mythology was a beautiful fairy turned into a fly (or in some versions, a butterfly), by a jealous queen. The insect Etain fell into a glass of milk and was swallowed by yet another queen, then reborn as a beautiful maiden. The name Etain not only survives but is one of the most popular Irish names for girls in modern Ireland. With the transatlantic success of Aiden, which is resembles, we wonder if Etain doesn't have a future in the U.S.