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

Moby Thesaurus II by Grady Ward, 1.0:

28 Moby Thesaurus words for "adjective":
   adjectival, adverb, adverbial, adversative conjunction,
   attributive, conjunction, conjunctive adverb,
   coordinating conjunction, copulative, copulative conjunction,
   correlative conjunction, disjunctive, disjunctive conjunction,
   exclamatory noun, form class, form word, function class, gerundive,
   interjection, part of speech, participle, particle,
   past participle, perfect participle, preposition,
   present participle, subordinating conjunction, verbal adjective