Final answer:
A cold front is the leading edge of a mass of cold air replacing a warmer air mass. It advances warm air and typically moves eastward.
Step-by-step explanation:
A cold front is defined as the leading edge of a mass of cold air that is replacing a warmer air mass. It is usually associated with stormy weather and brings changes in temperature, humidity, and wind direction. A cold front typically advances warm air and is usually moving in an eastward direction.