Padlock/ˈpædlɑːk/ Definition 1 of 2Pro Tip 1/3Physical Security Padlocks are often associated with safety and preventing theft. They added a padlock to their fence for extra security. Pro Tip 2/3Portable Lock Padlocks are portable; you can use them in different locations, unlike fixed locks. He brought his padlock to secure his locker at the gym. Pro Tip 3/3Variety of Sizes Padlocks come in different sizes for diverse uses, from small boxes to large gates. She used a small padlock for her jewelry box.