The definition of a rooftop arms is a type of arms race that takes place on the roofs of buildings. This type of arms race is often seen in urban areas, where the rooftops of buildings are used as a battleground for rival gangs or groups. In this type of arms race, the participants use a variety of weapons, ranging from handguns to assault rifles, to fight for control of the rooftops. The participants in a rooftop arms race are often armed with the same type of weapons, and the competition can be fierce. This type of arms race can be extremely dangerous, as the participants are often in close proximity to each other and the weapons used can cause serious injury or death. It is important to note that this type of arms race is illegal in many countries, and can lead to serious legal consequences if caught.