When in reference to
depression, and depression-related illnesses, euthymia (also,
normothymia) refers to the state of being in a "normal", level mood; not having
hyperthymia (mood elevation),
hypothymia (depression), nor
dysthymia (hardcore depression).
Persons with bipolar disorder may, with or without the aid of medication, be euthymic for even years on end.
Euthymia is also a woman's name.
In the year 310 CE, there was the Holy Great Virgin-Martyress Euthymia (whose feast day is January 4) who, along with 6 other HGVMs (Alexandra, Claudia, Euphrasia, Matrona, Juliana, and Theodosa) , was arrested in the city of Amisa, and interrogated under orders of the Roman Emperor Maximian Galerius. These women confessed their Christianity, and were tortured quite thoroughly: beaten with canes, had their breasts cut off, hung up and ripped with hooks, and then burned alive in an oven.
A couple hundred years later, in what would have been 573 CE, if I am doing my maths correctly, Euthymia appeared to one Saint Alypios in a vision, and told him to go to Adrianopolis to found a church for her. He did, on top of a pagan temple and graveyard, filled with a great many devils. Silly Alypios.
Then, in 1197 CE someone else built a womens' monastery in the name of the HGVM Euthymia; none other than the ArchBishop of Novgorod himself, the Sainted Martyrii!