Noun

1. an attack of depression or anxiety so severe that it prevents a person from continuing to function normally
   • 1887, George Gissing, Thyrza

     There was organic disease, and there was what is vaguely called nervous breakdown; it was too clear that Mr. Newthorpe must count upon very moderate activity either of mind or body henceforth.

   • 1915, P. G. Wodehouse, Something New

     ...will you kindly think up at your earliest convenience some plan for politely ejecting this Mr Chalmers of yours from our humble home?--because if you don't, I'm going to have a nervous breakdown.