Lock up Definition 1 of 4Pro Tip 1/3Security Focus Used when emphasizing actions taken for safety and to prevent unauthorized access. Did you lock up the bikes after the ride? Pro Tip 2/3Ending the Day Commonly refers to the final act of securing everything at day's end. Lock up the shop before you leave. Pro Tip 3/3Routine Reminder Often used as a reminder or instruction to ensure everything is secured. Remember to lock up when you're done.