The Collaborative International Dictionary of English v.0.48:

Lawless \Law"less\, a.
   1. Contrary to, or unauthorized by, law; illegal; as, a
      lawless claim.
      [1913 Webster]

            He needs no indirect nor lawless course. --Shak.
      [1913 Webster]

   2. Not subject to, or restrained by, the law of morality or
      of society; as, lawless men or behavior.
      [1913 Webster]

   3. Not subject to the laws of nature; uncontrolled.
      [1913 Webster]

            Or, meteorlike, flame lawless through the void.
                                                  --Pope.
      -- Law"less*ly, adv. -- Law"less*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

lawless
    adj 1: without law or control; "the system is economically
           inefficient and politically anarchic" [syn: anarchic,
           anarchical, lawless]
    2: lax in enforcing laws; "a wide-open town" [syn: wide-open,
       lawless]
    3: disobedient to or defiant of law; "lawless bands roaming the
       plains" [syn: lawless, outlaw(a)]

Moby Thesaurus II by Grady Ward, 1.0:

85 Moby Thesaurus words for "lawless":
   actionable, against the law, anarchic, anarchical, anarchistic,
   anomic, black-market, bootleg, chaotic, chargeable, contraband,
   contrary to law, corrupt, criminal, crooked, dishonest,
   disobedient, felonious, flagitious, flawed, froward, headstrong,
   heady, illegal, illegitimate, illicit, impermissible,
   indisciplined, iniquitous, insubordinate, irregular, irresponsible,
   justiciable, larcenous, licentious, mutinous, naughty, nefarious,
   nonconforming, nonconstitutional, nonlegal, nonlicit, obstinate,
   outlaw, outlawed, punishable, rampant, recusant, reinless,
   self-willed, sinful, transgressive, treacherous, triable,
   unaccountable, unallowed, unauthorized, unbridled, unchecked,
   uncomplying, unconstitutional, uncontrolled, uncurbed,
   under-the-counter, under-the-table, undisciplined, unduteous,
   undutiful, ungoverned, unlawful, unofficial, unreined,
   unrestrained, unruly, unstatutory, unwarrantable, unwarranted,
   venal, villainous, violative, wayward, wicked, wildcat, willful,
   wrongful



Bouvier's Law Dictionary, Revised 6th Ed (1856):

LAWLESS. Without law; without lawful control.