Definition of the word lock up

The phrase "lock up" originated in the mid-19th century in the context of securing a place or object by locking it up. The term "lock up" was first used in reference to jails and prisons, where prisoners were literally locked up in their cells at night as a security measure. The phrase gained popularity during this time and came to be used more broadly to describe the act of securing and making safe any place, object, or situation. Today, "lock up" can refer to anything from securing a building overnight to putting away leftovers in a refrigerator. The meaning of the phrase has evolved over time, but its origins can be traced back to the time-honored practice of securing prisoners in cells.