The Collaborative International Dictionary of English v.0.48:

epistemology \e*pis`te*mol"o*gy\, n. [Gr. ? knowledge + -logy.]
   The theory or science of the method or grounds of knowledge.
   [1913 Webster]

WordNet (r) 3.0 (2006):

epistemology
    n 1: the philosophical theory of knowledge

Moby Thesaurus II by Grady Ward, 1.0:

27 Moby Thesaurus words for "epistemology":
   aesthetics, axiology, casuistry, cosmology, ethics,
   first philosophy, gnosiology, logic, mental philosophy,
   metaphysics, moral philosophy, ontology, phenomenology,
   philosophastry, philosophic doctrine, philosophic system,
   philosophic theory, philosophical inquiry,
   philosophical speculation, philosophy, school of philosophy,
   school of thought, science of being, sophistry, theory of beauty,
   theory of knowledge, value theory