[1] : The Collaborative International Dictionary of English v.0.48

undefined \undefined\
   see defined.
see also:
defined 

[2] : WordNet (r) 2.0

undefined
     adj : not precisely limited, determined, or distinguished; "an
           undefined term"; "undefined authority"; "some undefined
           sense of excitement"; "vague feelings of sadness"; "a
           vague uneasiness" syn: vague ant: defined
see also:
vague defined 

[3] : Moby Thesaurus II by Grady Ward, 1.0

137 moby thesaurus words for "undefined":
   aleatoric, aleatory, all-knowing, all-powerful, all-seeing,
   all-wise, almighty, amorphic, amorphous, anarchic, anonymous,
   baggy, blear, bleared, bleary, blobby, blurred, blurry, boundless,
   broad, chance, chancy, changeless, chaotic, characterless,
   confused, creating, creative, cryptonymic, cryptonymous, dark, dim,
   disordered, disorderly, eternal, eternally the same, everlasting,
   faint, featureless, feeble, filmy, foggy, formless, fuzzy, general,
   glorious, good, half-seen, half-visible, hallowed, hazy, highest,
   hit-or-miss, holy, ill-defined, immortal, immutable, imprecise,
   inaccurate, inchoate, incognito, incoherent, inconspicuous,
   indecisive, indefinable, indefinite, indeterminable, indeterminate,
   indistinct, indistinguishable, inexact, infinite, inform,
   innominate, just, kaleidoscopic, lax, limitless, loose, loving,
   low-profile, luminous, lumpen, majestic, making, merciful,
   merely glimpsed, misty, nameless, nondescript, nonspecific,
   numinous, obscure, omnipotent, omnipresent, omniscient, one,
   orderless, out of focus, pale, permanent, perpetual, radiant,
   random, sacred, semivisible, shadowed forth, shadowy, shapeless,
   shaping, sovereign, stochastic, supreme, sweeping, timeless,
   ubiquitous, unacknowledged, unbounded, uncertain, unchanging,
   unclear, undesignated, undestined, undetermined, unidentified,
   unknown, unlimited, unnamed, unordered, unorganized, unplain,
   unrecognizable, unspecified, vague, veiled, weak, without a name

Undefined >> U Words
Undefined, definition of term: Undefined
undefined_pag1.html