Satisfying stimulation of the senses.
From Wikipedia circa 18-Aug-2012
URL: http://en.wikipedia.org/wiki/Pleasure
Pleasure describes the broad class of mental states that humans and other animals experience as positive, enjoyable, or worth seeking. It includes more specific mental states such as happiness, entertainment, enjoyment, ecstasy, and euphoria. In psychology, the pleasure principle describes pleasure as a positive feedback mechanism, motivating the organism to recreate in the future the situation which it has just found pleasurable. According to this theory, organisms are similarly motivated to avoid situations that have caused pain in the past.
The experience of pleasure is subjective and different individuals will experience different kinds and amounts of pleasure in the same situation. Many pleasurable experiences are associated with satisfying basic biological drives, such as eating, exercise or sex. Other pleasurable experiences are associated with social experiences and social drives, such as the experiences of accomplishment, recognition, and service. The appreciation of cultural artifacts and activities such as art, music, and literature is often pleasurable.
Link to Wikipedia article on Pleasure
Book Excerpts
Epicurus emphasized, though, that “pleasure” does not necessarily mean sensual pleasure–like eating chocolate, for instance. Values such as friendship and the appreciation of art also count. Moreover, the enjoyment of life required the old Greek ideals of self-control, temperance, and serenity. Desire must be curbed, and serenity will help us to endure pain.
– Jostein Gaarder, in Sophie’s World: A Novel About the History of Philosophy
Sources of Pleasure
Eating
Sex
Perceiving beauty