noun

• (medicine, now chiefly historical) Medicine as practised by an empiric, founded on mere experience, without the aid of science or a knowledge of principles; folk medicine, quackery.
• (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.)
• A pursuit of knowledge purely through experience, especially by means of observation and sometimes by experimentation.
• (social sciences, political science, sociology) used to describe research based on methodology shaped from empirical philosophy (see above), e.g. surveys, statistics, etc.