What is meant by the term 'black ice'?

Answer 1

Black ice is when it rains, and the temperatures are so low that the rain freezes. At that point the ice cannot be seen because it still appears blank.

Answer 2

Black ice is a thin layer of transparent ice that forms on roads and other surfaces, making it extremely slippery. It tends to blend in with the pavement, giving it its "black" appearance, and can be difficult to see, especially at night or in low light conditions. Driving over black ice can be very dangerous as it reduces traction and can lead to accidents.