I'm adding here something further with regard to the introduction of the article on the Determinents of Happiness mentioning Aristotle's definition of happiness ("Happiness is the meaning and the purpose of life, the whole aim, and the end of human existence.”- see post 2 above). Most people haven't been educated about Epicurus' take on happiness, (and if they are, their understanding is often over-simplified). Letter to Menoeceus says: "We must then meditate on the things that make our happiness, seeing that when that is with us we have all, but when it is absent we do all to win it." Perhaps Epicurus had other succinct definitions (perhaps in his book "On Life Courses" which is lost to us). But we do have the Cicero's Torquatus section and the Wall of Diogenes of Oinoanda.
There are a number of threads discussing what is happiness, such as this one as well as whole sub-forums. These may all need to be sorted and refreshed, and then I'll add more links so that we can all clearly reference Epicurus' take on happiness.