The Collaborative International Dictionary of English v.0.48:

Padlock \Pad"lock`\, v. t. [imp. & p. p. Padlocked; p. pr. &
   vb. n. Padlocking.]
   To fasten with, or as with, a padlock; to stop; to shut; to
   confine as by a padlock. --Milton. Tennyson.
   [1913 Webster]