To stop functioning or operating, typically due to a mechanical failure. The car broke down on the highway, leaving us stranded.
To analyze or deconstruct something into smaller parts for better understanding. The teacher broke down the complex topic into simpler concepts for the students.
To lose control of one's emotions, often resulting in crying. She broke down in tears when she heard the news.
To decompose or decay, especially in reference to organic matter. The compost will break down over time, enriching the soil.
To overcome or remove a barrier or obstacle. The negotiator worked hard to break down the resistance between the two parties.