The Collaborative International Dictionary of English v.0.48:

Mislay \Mis*lay"\, v. t. [imp. & p. p. Mislaid; p. pr. & vb.
   n. Mislaying.]
   [1913 Webster]
   1. To lay in a wrong place; to ascribe to a wrong source.
      [1913 Webster]

            The fault is generally mislaid upon nature. --Locke.
      [1913 Webster]

   2. To lay in a place not recollected; to misplace; to lose.
      [1913 Webster +PJC]

            The . . . charter, indeed, was unfortunately
            mislaid: and the prayer of their petition was to
            obtain one of like import in its stead. --Hallam.
      [1913 Webster]

WordNet (r) 3.0 (2006):

mislaid
    adj 1: lost temporarily; as especially put in an unaccustomed or
           forgotten place; "the mislaid hat turned up eventually";
           "misplaced tickets" [syn: mislaid, misplaced]