The Collaborative International Dictionary of English v.0.48:

Introductory \In`tro*duc"to*ry\, a. [L. itroductorius: cf. F.
   introductoire.]
   Serving to introduce something else; leading to the main
   subject or business; preliminary; prefatory; as, introductory
   proceedings; an introductory discourse.
   [1913 Webster]

WordNet (r) 3.0 (2006):

introductory
    adj 1: serving to open or begin; "began the slide show with some
           introductory remarks"
    2: serving as a base or starting point; "a basic course in
       Russian"; "basic training for raw recruits"; "a set of basic
       tools"; "an introductory art course" [syn: basic,
       introductory]
    3: serving as an introduction or preface [syn: introductory,
       prefatorial, prefatory]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "introductory":
   abecedarian, aboriginal, antenatal, autochthonous, autodidactic,
   baptismal, basic, beginning, budding, coeducational, creative,
   cultural, didactic, disciplinary, edifying, educating, educational,
   educative, elemental, elementary, embryonic, enlightening,
   exhortatory, fetal, first, formative, foundational, fundamental,
   gestatory, homiletic, hortatory, illuminating, in embryo,
   in its infancy, in the bud, inaugural, inceptive, inchoate,
   inchoative, incipient, incunabular, inductive, infant, infantile,
   informative, initial, initiative, initiatory, instructive,
   introductive, inventive, lecturing, nascent, natal, opening,
   original, parturient, postnatal, preaching, preceptive, prefatory,
   pregnant, preliminary, preludial, prelusive, prenatal, preparative,
   preparatory, primal, primary, prime, primeval, primitive,
   primogenial, procreative, proemial, propaedeutic, rudimental,
   rudimentary, self-teaching, teaching, tuitionary, ur