The Collaborative International Dictionary of English v.0.48:

Aimless \Aim"less\, a.
   Without aim or purpose; as, an aimless life. --
   Aim"less*ly, adv. -- Aim"less*ness, n.
   [1913 Webster]

WordNet (r) 3.0 (2006):

aimless
    adj 1: aimlessly drifting [syn: adrift(p), afloat(p),
           aimless, directionless, planless, rudderless,
           undirected]
    2: continually changing especially as from one abode or
       occupation to another; "a drifting double-dealer"; "the
       floating population"; "vagrant hippies of the sixties" [syn:
       aimless, drifting, floating, vagabond, vagrant]

Moby Thesaurus II by Grady Ward, 1.0:

100 Moby Thesaurus words for "aimless":
   amorphous, by the way, capricious, casual, causeless, chance,
   designless, desultory, deviative, digressive, disarticulated,
   discontinuous, discursive, disjunct, disordered, dispersed,
   disproportionate, driftless, dysteleological, empty, episodic,
   erratic, excursive, feckless, fitful, formless, frivolous, garbled,
   gratuitous, haphazard, hit-or-miss, immethodical, importless,
   impotent, inane, inchoate, incoherent, indiscriminate, ineffective,
   ineffectual, inexplicable, insignificant, irregular, loose,
   maundering, meaningless, mindless, misshapen, no go,
   nonconnotative, nondenotative, nonsymmetrical, nonsystematic,
   nonuniform, null, of no use, orderless, phatic, planless,
   pointless, promiscuous, purportless, purposeless, rambling, random,
   roving, scrambled, senseless, shapeless, spasmodic, sporadic,
   stochastic, straggling, straggly, stray, superfluous, systemless,
   unaccountable, unarranged, unavailing, unclassified, undirected,
   ungraded, unjoined, unmeaning, unmethodical, unmotivated,
   unordered, unorganized, unsignificant, unsorted, unsymmetrical,
   unsystematic, ununiform, useless, vagrant, vague, wandering,
   wanton, wayward