The Collaborative International Dictionary of English v.0.48:

Nominative \Nom"i*na*tive\, a. [L. nominativus belonging to a
   name, nominative.] (Gram.)
   Giving a name; naming; designating; -- said of that case or
   form of a noun which stands as the subject of a finite verb.
   -- n. The nominative case.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nominative
    adj 1: serving as or indicating the subject of a verb and words
           identified with the subject of a copular verb;
           "nominative noun endings"; "predicate nominative"
    2: named; bearing the name of a specific person; "nominative
       shares of stock" [syn: nominative, nominal]
    3: appointed by nomination [syn: nominated, nominative]
    n 1: the category of nouns serving as the grammatical subject of
         a verb [syn: nominative, nominative case, subject
         case] [ant: oblique, oblique case]

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "nominative":
   abessive, ablative, accusative, adessive, allative, appellative,
   approximative, byname, case, cognominal, common case, dative,
   delative, denominative, diminutive, elative, epithetic, eponymic,
   eponymous, essive, formal, genitive, honorific, hypocoristic,
   illative, in name only, inessive, instrumental, lative, local case,
   locative, nominal, objective case, oblique case, perlative,
   possessive case, prepositional, quasi, self-called,
   self-christened, self-styled, so-called, soi-disant, subject case,
   sublative, superessive, terminative, titular, translative,
   vocative, would-be