The Collaborative International Dictionary of English v.0.48:

Lappet \Lap"pet\, n. [Dim. of lap a fold.]
   A small decorative fold or flap, esp. of lace or muslin, in a
   garment or headdress. --Swift.
   [1913 Webster]

   Lappet moth (Zool.), one of several species of bombycid
      moths, which have stout, hairy caterpillars, flat beneath.
      Two common American species (Gastropacha Americana, and
      Tolype velleda) feed upon the apple tree.
      [1913 Webster]