unsystematic

from WordNet (r) 3.0 (2006)

unsystematic
    adj 1: lacking systematic arrangement or method or organization;
           "unsystematic and fragmentary records"; "he works in an
           unsystematic manner" [ant: {systematic}]

from Moby Thesaurus II by Grady Ward, 1.0

121 Moby Thesaurus words for "unsystematic":
      aimless, amorphous, broken, capricious, careening, casual, catchy,
      changeable, changing, choppy, desultory, deviating, deviative,
      deviatory, different, disarticulated, disconnected, discontinuous,
      disjunct, disordered, disorderly, dispersed, disproportionate,
      divaricate, divergent, diversified, diversiform, eccentric, erose,
      erratic, fitful, flickering, fluctuating, formless, frivolous,
      gratuitous, guttering, halting, haphazard, herky-jerky,
      heteroclite, hit-or-miss, immethodical, impulsive, inchoate,
      incoherent, inconsistent, inconstant, indiscriminate, intermittent,
      intermitting, irregular, jagged, jerky, lurching, meaningless,
      mercurial, misshapen, motley, mutable, nonconformist, nonstandard,
      nonsymmetrical, nonsystematic, nonuniform, orderless, patchy,
      planless, pluralistic, promiscuous, ragged, rambling, random,
      rough, scrappy, senseless, shapeless, snatchy, spasmatic, spasmic,
      spasmodic, spastic, sporadic, spotty, staggering, straggling,
      straggly, systemless, unarranged, uncertain, unclassified,
      undirected, unequable, unequal, uneven, ungraded, unjoined,
      unmethodical, unmetrical, unordered, unorganized, unorthodox,
      unregular, unrhythmical, unsettled, unsorted, unstable, unsteady,
      unsymmetrical, ununiform, vague, variable, variegated, variform,
      various, varying, veering, wandering, wavering, wobbling, wobbly