e·pis·te·mol·o·gy 
(ĭ-pĭs′tə-mŏlə-jē)
(ĭ-pĭs′tə-mŏlə-jē)n.
The branch of philosophy that examines the nature of knowledge, its presuppositions and foundations, and its extent and validity.
[Greek epistēmē, knowledge (from epistasthai, epistē-, to understand : epi-, epi- + histasthai, middle voice of histanai, to place, determine; see stā- in the Appendix of Indo-European roots) + -LOGY.]
e·pis′te·mo·logi·cal (-mə-lŏjĭ-kəl) adj.
e·pis′te·mo·logi·cal·ly adv.
e·pis′te·molo·gist n.