hedonism

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Pursuit of or devotion to pleasure, especially to the pleasures of the senses.
• noun Philosophy The ethical doctrine holding that only what is pleasant or has pleasant consequences is intrinsically good.
• noun Psychology The doctrine holding that behavior is motivated by the desire for pleasure and the avoidance of pain.

from The Century Dictionary.

• noun The doctrine of Aristippus and the Cyrenaic school of Greek philosophers, that the pleasure of the moment is the only possible end, that one kind of pleasure is not to be preferred to another, and that a man should in the interest of pleasure govern his pleasures and not be governed by them; hence, that ethical doctrine which regards pleasure or happiness as the highest good.

from the GNU version of the Collaborative International Dictionary of English.

• noun The doctrine of the Hedonic sect; the pursuit of pleasure as a matter of ethical principle.
• noun The ethical theory which finds the explanation and authority of duty in its tendency to give pleasure.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun ethics The belief that pleasure or happiness is the highest good in life. Some hedonists, such as the Epicureans, have insisted that pleasure of the entire mind, not just pleasure of the senses, is the highest good.
• noun A general devotion to the pursuit of pleasure.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the pursuit of pleasure as a matter of ethical principle
• noun an ethical system that evaluates the pursuit of pleasure as the highest good