The Collaborative International Dictionary of English v.0.48:

Descriptive \De*scrip"tive\, a. [L. descriptivus: cf. F.
   descriptif.]
   Tending to describe; having the quality of representing;
   containing description; as, a descriptive figure; a
   descriptive phrase; a descriptive narration; a story
   descriptive of the age.
   [1913 Webster]

   Descriptive anatomy, that part of anatomy which treats of
      the forms and relations of parts, but not of their
      textures.

   Descriptive geometry, that branch of geometry. which treats
      of the graphic solution of problems involving three
      dimensions, by means of projections upon auxiliary planes.
      --Davies & Peck (Math. Dict. ) -- De*scrip"tive*ly, adv.
      -- De*scrip"tive*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

descriptive
    adj 1: serving to describe or inform or characterized by
           description; "the descriptive variable"; "a descriptive
           passage" [ant: undescriptive]
    2: describing the structure of a language; "descriptive grammar"
       [ant: normative, prescriptive]

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "descriptive":
   constructional, constructive, definitional, delineative, depictive,
   diagnostic, exegetic, expositive, expressive, faithful,
   glottochronological, grammatic, graphemic, graphic, hermeneutic,
   interpretational, interpretive, lexicographic, lexicological,
   lexicostatistical, lifelike, lingual, linguistic, metalinguistic,
   morphological, morphophonemic, naturalistic, philological,
   phonemic, phonetic, phonological, psycholinguistic, realistic,
   representative, semantic, semeiological, structural,
   symptomatological, syntactic, tropological, true to life, vivid,
   well-drawn