Definition of the word seal off

The phrase "seal off" can be traced back to the late 19th century, when it was used in a nautical context to describe the act of closing the hatches and doors of a ship's hold to prevent the entry or escape of water. This usage derived from the fact that a sealed-off hold could be flooded to help stabilize the ship during rough seas, a common maritime practice known as flooding the tanks. The term's applicability to non-nautical contexts began to emerge during the 20th century, as the concept of containing or isolating something gained broader relevance outside of marine environments. For example, during the Cold War, the phrase came to be associated with the military's efforts to block off potential enemy infiltration routes or quarantine contaminated zones. Today, "seal off" is commonly used in a variety of situations to refer to the prevention of outside influence or access to a confined area. It can be applied to blocking off a street during a parade, sealing off a crime scene to prevent evidence from being tampered with, or isolating contaminated areas during a hazardous materials spill. In each case, "seal off" emphasizes the critical importance of containing or securing a specific space, and preventing the wider contemporary context it evolved in is the heightened emphasis on the need for security and containment.