pad·lock 
(pădlŏk′)
(pădlŏk′)n.
A detachable lock with a U-shaped bar hinged at one end, designed to be passed through the staple of a hasp or a link in a chain and then snapped shut.
tr.v. pad·locked, pad·lock·ing, pad·locks
To lock up with or as if with a padlock.
[Middle English padlok : pad-, of unknown meaning + lok, lock; see LOCK1.]