The Collaborative International Dictionary of English v.0.48:

Philology \Phi*lol"o*gy\ (f[i^]*l[o^]l"[-o]*j[y^]), n. [L.
   philologia love of learning, interpretation, philology, Gr.
   filologi`a: cf. F. philologie. See Philologer.]
   1. Criticism; grammatical learning. [R.] --Johnson.
      [1913 Webster]

   2. The study of language, especially in a philosophical
      manner and as a science; the investigation of the laws of
      human speech, the relation of different tongues to one
      another, and historical development of languages;
      linguistic science.
      [1913 Webster]

   Note: Philology comprehends a knowledge of the etymology, or
         origin and combination of words; grammar, the
         construction of sentences, or use of words in language;
         criticism, the interpretation of authors, the
         affinities of different languages, and whatever relates
         to the history or present state of languages. It
         sometimes includes rhetoric, poetry, history, and
         antiquities.
         [1913 Webster]

   3. A treatise on the science of language.
      [1913 Webster] `

WordNet (r) 3.0 (2006):

philology
    n 1: the humanistic study of language and literature [syn:
         linguistics, philology]