Source : Webster's Revised Unabridged Dictionary (1913)

Regardless \Re*gard"less\, a.
   1. Having no regard; heedless; careless; as, regardless of
      life, consequences, dignity.

            Regardless of the bliss wherein he sat. --Milton.

   2. Not regarded; slighted. [R.] --Spectator.

   Syn: Heedless; negligent; careless; indifferent; unconcerned;
        inattentive; unobservant; neglectful. --
        {Re*gard"less*ly}, adv. -- {Re*gard"less*ness}, n.

Source : WordNet®

regardless
     adj : (usually followed by `of') without due thought or
           consideration; "careless of the consequences"; "the
           proverbial grasshopper--thoughtless of tomorrow";
           "crushing the blooms with regardless tread" [syn: {careless(p)},
            {thoughtless(p)}]
     adv : in spite of everything; without regard to drawbacks; "he
           carried on regardless of the difficulties" [syn: {irrespective},
            {disregardless}, {no matter}, {disregarding}]