Source : Webster's Revised Unabridged Dictionary (1913)

Inoffensive \In"of*fen"sive\, a. [Pref. in- not + offensiue: cf.
   F. inoffensif.]
   1. Giving no offense, or provocation; causing no uneasiness,
      annoyance, or disturbance; as, an inoffensive man, answer,
      appearance.

   2. Harmless; doing no injury or mischief. --Dryden.

   3. Not obstructing; presenting no interruption bindrance.
      [R.] --Milton.

            So have Iseen a river gintly glide In a smooth
            course, and inoffensive tide.         --Addison.
      -- {In"of*fen"sive*ly}, adv. -- {In"of*fen"sive*ness}, n.

Source : WordNet®

inoffensively
     adv : in a not unpleasantly offensive manner; "that wretched
           beast, the elephant, breathing inoffensively not a pace
           behind me" [ant: {offensively}]