1 : a failure of a machine to function : an occurrence in which a machine (such as a car) stops working [count] ▪ We had a breakdown on the highway. [=our car broke down on the highway; our car stopped working on the highway] ▪ The factory has had frequent equipment breakdowns. [noncount] ▪ Frequent equipment breakdown [=(more commonly) failure] has been a problem at the factory. 2 a [count] : the failure of a relationship or of an effort to discuss something
▪ There has been a breakdown of/in negotiations. [=negotiations have broken down; negotiations have failed] ▪ Both sides are to blame for the breakdown in communication. ▪ The irretrievable breakdown of a marriage can be grounds for divorce.
b : a failure that prevents a system from working properly [count] ▪ trying to prevent a breakdown of the health-care system [noncount] ▪ trying to prevent breakdown of the health-care system ▪ Analysts predict that the country is headed for economic breakdown. [=meltdown] 3 [count] : a sudden failure of mental or physical health that makes someone unable to live normally
▪ He suffered/had a breakdown after his wife died. ▪ a total physical/mental breakdown [=collapse] — see also nervous breakdown 4 : the process or result of showing the different parts of something in order to understand it more clearly [count] ▪ Doing/Providing a breakdown of the statistics into categories will take time. ▪ I want a detailed breakdown of the statistics into categories. [noncount] ▪ The library's database enables breakdown by title, author, and genre. 5 [noncount] : the process or result of separating a substance into simpler parts
▪ the breakdown of water into hydrogen and oxygen ▪ observing cell/tissue/protein breakdown ▪ a substance that resists breakdown — see also break down at ¹break