The Collaborative International Dictionary of English v.0.48:

Adjective \Ad"jec*tive\, v. t. [imp. & p. p. Adjectived; p.
   pr. & vb. n. Adjectiving.]
   To make an adjective of; to form or change into an adjective.
   [R.]
   [1913 Webster]

         Language has as much occasion to adjective the distinct
         signification of the verb, and to adjective also the
         mood, as it has to adjective time. It has . . .
         adjectived all three.                    --Tooke.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Adjective \Ad"jec*tive\ ([a^]d"j[e^]k*t[i^]v), a. [See
   Adjective, n.]
   [1913 Webster]
   1. Added to a substantive as an attribute; of the nature of
      an adjunct; as, an adjective word or sentence.
      [1913 Webster]

   2. Not standing by itself; dependent.
      [1913 Webster]

   Adjective color, a color which requires to be fixed by some
      mordant or base to give it permanency.
      [1913 Webster]

   3. Relating to procedure. "The whole English law, substantive
      and adjective." --Macaulay.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Adjective \Ad"jec*tive\, n. [L. adjectivum (sc. nomen), neut. of
   adjectivus that is added, fr. adjicere: cf. F. adjectif. See
   Adject.]
   1. (Gram.) A word used with a noun, or substantive, to
      express a quality of the thing named, or something
      attributed to it, or to limit or define it, or to specify
      or describe a thing, as distinct from something else.
      Thus, in phrase, "a wise ruler," wise is the adjective,
      expressing a property of ruler.
      [1913 Webster]

   2. A dependent; an accessory. --Fuller.
      [1913 Webster]

WordNet (r) 3.0 (2006):

adjective
    adj 1: of or relating to or functioning as an adjective;
           "adjectival syntax"; "an adjective clause" [syn:
           adjectival, adjective]
    2: relating to court practice and procedure as opposed to the
       principles of law; "adjective law" [syn: adjective,
       procedural] [ant: essential, substantive]
    n 1: a word that expresses an attribute of something
    2: the word class that qualifies nouns