Source : Webster's Revised Unabridged Dictionary (1913)

Overt \O"vert\, a. [OF. overt, F. ouvert, p. p. of OF. ovrir, F.
   ouvrir, to open, of uncertain origin; cf. It. aprire, OIt.
   also oprire, L. aperire to open, operire to cover, deoperire
   to uncover. Perch. from L. aperire influenced by F. couvrir
   to cover. Cf. {Aperient}, {Cover}.]
   1. Open to view; public; apparent; manifest.

            Overt and apparent virtues bring forth praise.
                                                  --Bacon.

   2. (Law) Not covert; open; public; manifest; as, an overt act
      of treason. --Macaulay.

            No person shall be convicted of treason unless on
            the testimony of two witnesses to the same overt
            act, or on confession in open court. --Constitution
      of the U. S.

   Note: In criminal law, an overt act is an open done in
         pursuance and manifestation of a criminal design; the
         mere design or intent not being punishable without such
         act. In English law, market overt is an open market; a
         pound overt is an open, uncovered pound.

Source : WordNet®

overt
     adj : open and observable; not secret or hidden; "an overt lie";
           "overt hostility"; "overt intelligence gathering" [syn:
            {open}] [ant: {covert}]