Source : Webster's Revised Unabridged Dictionary (1913)

Erroneous \Er*ro"ne*ous\, a. [L. erroneus, fr. errare to err.
   See {Err}.]
   1. Wandering; straying; deviating from the right course; --
      hence, irregular; unnatural. [Obs.] ``Erroneous
      circulation.'' --Arbuthnot.

            Stopped much of the erroneous light, which otherwise
            would have disturbed the vision.      --Sir I.
                                                  Newman.

   2. Misleading; misled; mistaking. [Obs.]

            An erroneous conscience commands us to do what we
            ought to omit.                        --Jer. Taylor.

   3. Containing error; not conformed to truth or justice;
      incorrect; false; mistaken; as, an erroneous doctrine;
      erroneous opinion, observation, deduction, view, etc. --
      {Er*ro"ne*ous*ly}, adv. -- {Er*ro"ne*ous*ness}, n.

Source : WordNet®

erroneously
     adv : in a mistaken manner; "he mistakenly believed it" [syn: {mistakenly}]