empiricism

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

• noun The view that experience, especially of the senses, is the only source of knowledge.
• noun Employment of empirical methods, as in science.
• noun An empirical conclusion.
• noun The practice of medicine that disregards scientific theory and relies solely on practical experience.

from The Century Dictionary.

• noun The character of being empirical; reliance on direct experience and observation rather than on theory; empirical method; especially, an undue reliance upon mere individual experience.
• noun In medicine, the practice of empirics; hence, quackery; the pretension of an ignorant person to medical skill.
• noun The metaphysical theory that all ideas are derived from sensuous experience—that is, that there are no innate or a priori conceptions.

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

• noun The method or practice of an empiric; pursuit of knowledge by observation and experiment.
• noun Specifically, a practice of medicine founded on mere experience, without the aid of science or a knowledge of principles; ignorant and unscientific practice; charlatanry; quackery.
• noun (Metaph.) The philosophical theory which attributes the origin of all our knowledge to experience.

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

• noun A pursuit of knowledge purely through experience, especially by means of observation and sometimes by experimentation.
• noun medicine, dated A practice of medicine founded on mere experience, without the aid of science or a knowledge of principles; ignorant and unscientific practice; the method or practice of an empiric.

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

• noun the application of empirical methods in any art or science
• noun (philosophy) the doctrine that knowledge derives from experience
• noun medical practice and advice based on observation and experience in ignorance of scientific findings