Preamble

n.	1.	A introductory portion; an introduction or preface, as to a book, document, etc.; specifically, the introductory part of a statute, which states the reasons and intent of the law.
v. t. & i.	1.	To make a preamble to; to preface; to serve as a preamble.

Noun	1.	preamble - a preliminary introduction to a statute or constitution (usually explaining its purpose)
Verb	1.	preamble - make a preliminary introduction, usually to a formal document

PREAMBLE. A preface, an introduction or explanation of what is to follow: that clause at the head of acts of congress or other legislatures which explains the reasons why the act is made. Preambles are also frequently put in contracts to, explain the motives of the contracting parties,
     2. A preamble is said to be the key of a statute, to open the minds of the makers as to the mischiefs which are to be remedied, and the objects which are to be accomplished by the provisions of the statutes. It cannot amount, by implication, to enlarge what is expressly given. 1 Story on Const. B 3, c. 6. How far a preamble is to be considered evidence of the facts it recites, see 4 M. & S. 532; 1 Phil. Ev. 239; 2 Russ. on Cr. 720; and see, generally, Ersk. L. of Scotl. 1, 1, 18; Toull. liv. 3, n. 318; 2 Supp. to Ves. jr. 239; 4 L. R. 55; Barr. on the Stat. 353, 370.

avant-propos, breakthrough, exordium, front matter, frontispiece, innovation, introduce, leap, postulate, preface, prefix, prefixture, preliminary, premise, presupposition, proem, prolegomena, prolegomenon, prolepsis, prologize, protasis, verse, voluntary