Eunoia is a rarely used medical term referring to a state of normal mental health. It comes from the Greek for well mind. [1] (http://www.dictionarybarn.com/EUNOIA.php)

In book eight of Nicomachean Ethics, Aristotle uses the term to refer to the kind and benevolent feelings of goodwill a spouse has which forms the basis for the ethical foundation of human life.[2] (http://www.mun.ca/animus/2001vol6/provencal6.htm)

Eunoia is also the title of a Christian Bök lipogram (ISBN 1552450929) which consists of chapters written using words limited to a single vowel; the book's title is the shortest word in the English language to include all five main vowels.