noun

• (philosophy) A doctrine which holds that the only or, at least, the most reliable source of human knowledge is experience, especially perception by means of the physical senses. (Often contrasted with rationalism.)
  "Empiricism teaches us that we are unceasingly and intimately in contact with a full, living, breathing Reality, that experience is a constant communion with the real."
• (social sciences, political science, sociology) Research methodology shaped from empirical philosophy (see above), e.g. surveys, statistics, etc.
• (medicine, now chiefly historical) Medicine as practised by an empiric, founded on mere (personal or anecdotal) experience, without the aid of science or a knowledge of principles.
  "Near-synonyms: folk medicine; quackery; charlatanry"