The Collaborative International Dictionary of English v.0.48:

Concealed \Con*cealed"\, a.
   Hidden; kept from sight; secreted. -- Con*ceal"ed*ly, adv.
   -- Con*ceal"ed*ness, n.
   [1913 Webster]

   Concealed weapons (Law), dangerous weapons so carried on
      the person as to be knowingly or willfully concealed from
      sight, -- a practice forbidden by statute.
      [1913 Webster]