209. When a warm air mass overtakes a cold air mass, which term is given to the contact surface?

A warm front is defined as the boundary where a warm air mass advances over a retreating cold air mass. This aligns with the question's description and distinguishes it from a cold front, which involves a cold air mass overtaking a warm air mass, and from waterspouts and line squalls, which are weather phenomena unrelated to the contact surface between air masses.