The Collaborative International Dictionary of English v.0.48:

Desultory \Des"ul*to*ry\, a. [L. desultorius, fr. desultor a
   leaper, fr. desilire, desultum, to leap down; de + salire to
   leap. See Saltation.]
   1. Leaping or skipping about. [Obs.]
      [1913 Webster]

            I shot at it [a bird], but it was so desultory that
            I missed my aim.                      --Gilbert
                                                  White.
      [1913 Webster]

   2. Jumping, or passing, from one thing or subject to another,
      without order or rational connection; without logical
      sequence; disconnected; immethodical; aimless; as,
      desultory minds. --Atterbury.
      [1913 Webster]

            He [Goldsmith] knew nothing accurately; his reading
            had been desultory.                   --Macaulay.
      [1913 Webster]

   3. Out of course; by the way; as a digression; not connected
      with the subject; as, a desultory remark.

   Syn: Rambling; roving; immethodical; discursive; inconstant;
        unsettled; cursory; slight; hasty; loose.
        [1913 Webster]

WordNet (r) 3.0 (2006):

desultory
    adj 1: marked by lack of definite plan or regularity or purpose;
           jumping from one thing to another; "desultory thoughts";
           "the desultory conversation characteristic of cocktail
           parties"

Moby Thesaurus II by Grady Ward, 1.0:

211 Moby Thesaurus words for "desultory":
   aberrant, aberrative, adrift, afloat, aimless, alternating,
   amorphous, broken, by the way, capricious, careening, casual,
   catchy, changeable, changeful, chaotic, choppy, circuitous,
   dancing, dangerous, departing, designless, deviable, deviant,
   deviating, deviative, deviatory, devious, digressive,
   disarticulated, disconnected, discontinuous, discursive, disjunct,
   disordered, disorderly, disorganized, dispersed, disproportionate,
   dizzy, eccentric, episodic, errant, erratic, excursive,
   fast and loose, fickle, fitful, flickering, flickery, flicky,
   flighty, flitting, fluctuating, fluttering, fluttery, formless,
   freakish, frivolous, giddy, gratuitous, guttering, halting,
   haphazard, hazardous, herky-jerky, heteroclite, hit-or-miss,
   immethodical, impetuous, impulsive, inchoate, incoherent,
   inconsistent, inconstant, indecisive, indirect, indiscriminate,
   infirm, insecure, insubstantial, intermittent, intermitting,
   irregular, irresolute, irresponsible, jerky, labyrinthine, loose,
   lurching, maundering, mazy, meandering, meaningless, mercurial,
   misshapen, moody, nonsymmetrical, nonsystematic, nonuniform,
   on-again-off-again, orderless, out-of-the-way, patchy, perilous,
   planetary, planless, precarious, promiscuous, provisional,
   purposeless, rambling, random, restless, risky, rough, roving,
   scatterbrained, scrappy, senseless, serpentine, shaky, shapeless,
   shifting, shifty, shuffling, slippery, snaky, snatchy, spasmatic,
   spasmic, spasmodic, spastic, spineless, spluttering, sporadic,
   spotty, sputtering, sputtery, staggering, straggling, straggly,
   stray, swerving, systemless, temporary, tentative, ticklish,
   treacherous, turning, twisting, unaccountable, unarranged,
   uncertain, unclassified, unconsidered, uncontrolled, undependable,
   undirected, undisciplined, unequal, uneven, unfaithworthy, unfixed,
   ungraded, unjoined, unmethodical, unmetrical, unordered,
   unorganized, unplanned, unpredictable, unregular, unreliable,
   unrestrained, unrhythmical, unsettled, unsolid, unsorted, unsound,
   unstable, unstable as water, unstaid, unsteadfast, unsteady,
   unsubstantial, unsure, unsymmetrical, unsystematic, untrustworthy,
   ununiform, vacillating, vagrant, vague, variable, veering,
   vicissitudinary, vicissitudinous, volatile, wandering, wanton,
   wavering, wavery, wavy, wayward, whimsical, winding, wishy-washy,
   wobbling, wobbly, zigzag