Final answer:
The term 'reverse lay' refers to a firefighting tactic where a supply line is laid out from the water source to the fire as the fire apparatus moves toward the fire.
Step-by-step explanation:
The term reverse lay describes an apparatus that lays out a supply line from the water source to the fire. This is a common tactic used by firefighters to ensure that there is a steady flow of water from the water source, such as a hydrant or a water tender, to the location of the fire. During this process, firefighters connect hoses to a fire hydrant and then lay them out towards the fire scene as the fire apparatus drives toward the fire, hence the term 'reverse' lay.