The Collaborative International Dictionary of English v.0.48:

Harmless \Harm"less\ (h[aum]rm"l[e^]s), a.
   1. Free from harm; unhurt; as, to give bond to save another
      harmless.
      [1913 Webster]

   2. Free from power or disposition to harm; innocent;
      inoffensive. " The harmless deer." --Drayton

   Syn: Innocent; innoxious; innocuous; inoffensive;
        unoffending; unhurt; uninjured; unharmed.
        --Harm"less*ly, adv.- Harm"less*ness, n. Harmonic

WordNet (r) 3.0 (2006):

harmlessly
    adv 1: in a harmless manner; "this is a harmlessly childish
           game" [ant: detrimentally, harmfully, noxiously]