(of a machine or motor vehicle) suddenly cease to function.
"his van broke down"
(of a person) have the vehicle they are driving cease to function.
"she broke down on the highway"
(of a relationship, agreement, or process) cease to continue; collapse.
"pay negotiations with management broke down"
synonyms: fail, collapse, founder, fall through, disintegrate; informalfizzle out
"pay negotiations broke down"
lose control of one's emotions when in a state of distress.
"if she had tried to utter a word, she would have broken down"
synonyms: burst into tears; More
(of a person's health or emotional control) fail or collapse.
"his health broke down under the strain of overwork"
2.
undergo chemical decomposition.
"waste products that break down into low-level toxic materials