Source : Webster's Revised Unabridged Dictionary (1913)

Resistless \Re*sist"less\, a.
   1. Having no power to resist; making no opposition. [Obs. or
      R.] --Spenser.

   2. Incapable of being resisted; irresistible.

            Masters' commands come with a power resistless To
            such as owe them absolute subjection. --Milton.
      -- {Re*sist"less*ly}, adv. -- {Re*sist"less*ness}, n.