The word breakdown has several related meanings:

1. A mechanical failure when something stops working. When a car has a breakdown on the highway, its engine quits or a crucial part fails, leaving it stranded. Machines, computers, and appliances can all experience breakdowns when their parts wear out or malfunction. You might hear someone say their printer had a breakdown right before a big assignment was due.
2. A failure in communication, relationships, or systems. When negotiations reach a breakdown, the two sides can no longer find common ground and talks collapse. A breakdown in communication happens when people stop understanding each other or sharing information effectively. Friendships can experience breakdowns when trust erodes or conflicts go unresolved.
3. An analysis that divides something into its parts. A teacher might give you a breakdown of how your grade is calculated: 40% tests, 30% homework, 20% projects, and 10% participation. A coach might provide a breakdown of the opposing team's strengths and weaknesses. This kind of breakdown helps you understand how different pieces fit together to form the whole.

The word suggests something that was working or whole becoming separated, stopping, or being analyzed into smaller components.