sporadic

sporadic
    adj 1: recurring in scattered and irregular or unpredictable
           instances; "a city subjected to sporadic bombing raids"
           [ant: {continual}]
    

Sporadic \Spo*rad"ic\ (-r[a^]d"[i^]k), a. [Gr. ? scattered, fr.
   ?, ?, scattered, fr. ? to sow seed, to scatter like seed: cf.
   F. sporadique. See {Spore}.]
   Occurring singly, or apart from other things of the same
   kind, or in scattered instances; separate; single; as, a
   sporadic fireball; a sporadic case of disease; a sporadic
   example of a flower.
   [1913 Webster]

   {Sporadic disease} (Med.), a disease which occurs in single
      and scattered cases. See the Note under {Endemic}, a.
      [1913 Webster]
    

165 Moby Thesaurus words for "sporadic":
      aimless, amorphous, broadcast, broken, capricious, careening,
      casual, catching, catchy, chance, changeable, changing, choppy,
      communicable, contagious, desultory, deviating, deviative,
      deviatory, different, diffuse, disarticulated, disconnected,
      discontinuous, discrete, disjunct, disordered, disorderly,
      dispersed, dispread, disproportionate, disseminated, dissipated,
      distributed, divaricate, divergent, diversified, diversiform,
      eccentric, endemic, epidemial, epidemic, epiphytotic, epizootic,
      erose, erratic, few, fitful, flickering, fluctuating, formless,
      frivolous, gratuitous, guttering, halting, haphazard, herky-jerky,
      heteroclite, hit-or-miss, immethodical, impulsive, inchoate,
      incoherent, inconsistent, inconstant, indiscriminate, infectious,
      infective, inoculable, intermittent, intermitting, irregular,
      jagged, jerky, lurching, meaningless, mercurial, misshapen, motley,
      mutable, nonconformist, nonstandard, nonsymmetrical, nonsystematic,
      nonuniform, occasional, on-again-off-again, orderless, pandemic,
      patchy, periodical, pestiferous, pestilential, planless,
      pluralistic, promiscuous, ragged, rambling, random, rare, rough,
      scarce, scattered, scrappy, seldom, senseless, separate, shapeless,
      single, snatchy, sparse, spasmatic, spasmic, spasmodic,
      spasmodical, spastic, spotty, spread, spreading, staggering,
      straggling, straggly, strewn, strown, systemless, taking,
      unarranged, uncertain, unclassified, uncommon, undirected,
      unequable, unequal, uneven, unexpected, unfrequent, ungraded,
      unjoined, unmethodical, unmetrical, unordered, unorganized,
      unorthodox, unregular, unrhythmical, unsettled, unsorted, unstable,
      unsteady, unsymmetrical, unsystematic, ununiform, vague, variable,
      variegated, variform, various, varying, veering, wandering,
      wavering, widespread, wobbling, wobbly, zymotic