prelude
I
noun
beginning, commencement, exordium, foreword, inauguration, inception, induction, initiation, introduction, opening, outset, overture, preamble, preface, preliminary part, prelusion, preparation, proem, prologue, prooemium, start
II
index
overture, preamble, preface (noun), preface (verb), threshold (commencement)
Burton's Legal Thesaurus.
William C. Burton.
2006