The Collaborative International Dictionary of English v.0.48:

Declaratory \De*clar"a*to*ry\, a. [Cf. F. d['e]claratoire.]
   Making declaration, explanation, or exhibition; making clear
   or manifest; affirmative; expressive; as, a clause
   declaratory of the will of the legislature.
   [1913 Webster]

   Declaratory act (Law), an act or statute which sets forth
      more clearly, and declares what is, the existing law.
      [1913 Webster]

WordNet (r) 3.0 (2006):

declaratory
    adj 1: relating to the use of or having the nature of a
           declaration [syn: declarative, declaratory,
           asserting(a)] [ant: interrogative, interrogatory]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

DECLARATORY. Something which explains, or ascertains what before was
uncertain or doubtful; as a declaratory statute, which is one passed to put
an end to a doubt as to what the law is, and which declares what it is, and
what it has been. 1 Bl. Com. 86.