Is it farther or further?
"a collapse," 1832, from break (v.) + down (adv.). The verbal phrase is attested from late 14c. The noun, specifically of machinery, is from 1838; meaning "an analysis in detail" is from 1936. Nervous breakdown is from 1905.
breakdown break·down (brāk'doun')n.
The act or process of failing to function or continue.
A typically sudden collapse in physical or mental health.
Disintegration or decomposition into parts or elements.