Wikimedia
Wikipedia: Aesthetics (Or Esthetics)
A Wikipedia Encyclopedia article that defines aesthetics and discusses it in a number of contexts, including literature. A broad definition of the term is provided at the top of the page, and then links are provided to discussions of the...
ArtLex
Art Lex: Aesthetics
Definition of "aesthetics" according to ArtLex, a dictionary of art terms. Includes links to other important terms as well. A good place to start.