The Collaborative International Dictionary of English v.0.48:

Amorphous \A*mor"phous\, a. [Gr. ?; 'a priv. + morfh` form.]
   1. Having no determinate form; of irregular; shapeless.
      --Kirwan.
      [1913 Webster]

   2. Without crystallization in the ultimate texture of a solid
      substance; uncrystallized.
      [1913 Webster]

   3. Of no particular kind or character; anomalous.
      [1913 Webster]

            Scientific treatises . . . are not seldom rude and
            amorphous in style.                   --Hare.
      [1913 Webster] -- A*mor"phous*ly, adv. --
      A*mor"phous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

amorphous
    adj 1: having no definite form or distinct shape; "amorphous
           clouds of insects"; "an aggregate of formless particles";
           "a shapeless mass of protoplasm" [syn: amorphous,
           formless, shapeless]
    2: lacking the system or structure characteristic of living
       bodies [syn: amorphous, unstructured]
    3: without real or apparent crystalline form; "an amorphous
       mineral"; "amorphous structure" [syn: amorphous,
       uncrystallized, uncrystallised]

Moby Thesaurus II by Grady Ward, 1.0:

189 Moby Thesaurus words for "amorphous":
   aberrant, abnormal, adrift, afloat, aimless, aleatoric, aleatory,
   alternating, amorphic, anarchic, anomalistic, anomalous, baggy,
   blind, blobby, blurred, blurry, broad, capricious, casual, chance,
   chancy, changeable, changeful, chaotic, characterless,
   clear as mud, cloudy, confused, dark, desultory, deviable,
   deviative, different, dim, disarticulated, discontinuous, disjunct,
   disordered, disorderly, dispersed, disproportionate, divergent,
   dizzy, eccentric, erratic, fast and loose, featureless, fickle,
   fitful, flickering, flighty, flitting, fluctuating, foggy,
   formless, freakish, frivolous, fuzzy, general, giddy, gratuitous,
   haphazard, hazy, heteroclite, heteromorphic, hit-or-miss,
   ill-defined, immethodical, impetuous, imprecise, impulsive,
   inaccurate, inchoate, incoherent, inconsistent, inconstant,
   indecisive, indefinable, indefinite, indeterminable, indeterminate,
   indiscriminate, indistinct, inexact, infirm, inform, irregular,
   irresolute, irresponsible, kaleidoscopic, lax, loose, lumpen, mazy,
   meaningless, mercurial, misshapen, misty, moody, muddy, murky,
   nebulous, nondescript, nonspecific, nonsymmetrical, nonsystematic,
   nonuniform, obscure, opaque, orderless, planless, promiscuous,
   rambling, random, restless, roving, scatterbrained, senseless,
   shadowed forth, shadowy, shapeless, shifting, shifty, shuffling,
   spasmodic, spineless, sporadic, stochastic, straggling, straggly,
   stray, straying, subnormal, sweeping, systemless, transcendent,
   unaccountable, unarranged, uncertain, unclassified, unclear,
   uncontrolled, undefined, undependable, undestined, undetermined,
   undirected, undisciplined, unfixed, unformed, ungraded, unjoined,
   unmethodical, unnatural, unordered, unorganized, unplain,
   unpredictable, unreliable, unrestrained, unsettled, unshaped,
   unsorted, unspecified, unstable, unstable as water, unstaid,
   unsteadfast, unsteady, unsymmetrical, unsystematic, ununiform,
   vacillating, vagrant, vague, variable, veiled, vicissitudinary,
   vicissitudinous, volatile, wandering, wanton, wavering, wavery,
   wavy, wayward, whimsical, wishy-washy