The Collaborative International Dictionary of English v.0.48:

Needless \Nee"dless\, a.
   1. Having no need. [Obs.]
      [1913 Webster]

            Weeping into the needless stream.     --Shak.
      [1913 Webster]

   2. Not wanted; unnecessary; not requisite; as, needless
      labor; needless expenses.
      [1913 Webster]

   3. Without sufficient cause; groundless; causeless. "Needless
      jealousy." --Shak.
      [1913 Webster] -- Need"less*ly, adv. --
      Need"less*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

needless
    adj 1: unnecessary and unwarranted; "a strikers' tent camp...was
           burned with needless loss of life" [syn: gratuitous,
           needless, uncalled-for]

Moby Thesaurus II by Grady Ward, 1.0:

30 Moby Thesaurus words for "needless":
   de trop, dispensable, excess, excessive, expendable, expletive,
   gratuitous, in excess, inessential, naturally, nonessential,
   obviously, pleonastic, prolix, redundant, spare, supererogatory,
   superfluous, tautologic, tautological, tautologous, to spare,
   uncalled-for, unessential, unnecessary, unneeded, unrequired,
   unwanted, useless, verbose