Words that are generally misused in everyday speech are like most of the words that the philosopher cannot avoid using because they name great ideas or aspects of them. In some case another word might be introduced to remedy the ambiguity, The word "happiness" is a prime example.
There is, on the one hand, the purely psychological meaning of "happiness" when that word is used to refer to the satisfaction or contentment an individual feels in getting what is wanted. In this meaning, one can feel happy one day and not happy the next day, but in either meaning, the individual is reporting an experienced subjective feeling. The primary point to remember here is that, in their psychological meanings, happiness and unhappiness are experienceable feelings. That is not the case when we come to the ethical or moral meaning of the word.
In its ethical or moral meaning, the word "happiness" refers to a life well lived, a whole life that is morally good because it is the product of virtue (or the habit of right desire) accompanied by the blessing of good fortune.
In this sense of the word, happiness is not something we feel or experience. In no moment of period of time can happiness in this sense be felt or experienced. During one's life, one may be on the road to happiness, one may be described as becoming happy, but one cannot be said to be happy. Only when your life is over can someone else commenting on your life declare that you had lived a good life and can be described as a person who had achieved happiness.
Happiness in heaven and out of time is experienced in eternity and is experienced by those who enjoy the beatific vision. (In regard to this meaning, see Beatitude.)
Adler's Philosophical Dictionary (1995)
Great Ideas from the Great Books (1963)
by Mortimer J. Adler