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]

Moby Thesaurus II by Grady Ward, 1.0:

32 Moby Thesaurus words for "philology":
   bowwow theory, comparative linguistics, derivation,
   descriptive linguistics, dialectology, dingdong theory, etymology,
   glossematics, glossology, glottochronology, glottology, grammar,
   graphemics, historical linguistics, language study, lexicology,
   lexicostatistics, linguistic geography, linguistic science,
   linguistics, mathematical linguistics, morphology, morphophonemics,
   paleography, phonetics, phonology, psycholinguistics, semantics,
   sociolinguistics, structuralism, syntactics,
   transformational linguistics