Philosophy is the study of general and fundamental problems, such as those connected with reality, existence, knowledge, values, reason, mind, and language.
Philosophy is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational argument. In more casual speech, by extension, "philosophy" can refer to "the most basic beliefs, concepts, and attitudes of an individual or group".
The word "philosophy" comes from the Ancient Greek φιλοσοφία (philosophia), which literally means "love of wisdom". The introduction of the terms "philosopher" and "philosophy" has been ascribed to the Greek thinker Pythagoras.
SOURCE: Wikipedia article “Philosophy”, which is released under the Creative Commons Attribution-Share-Alike License 3.0.