Definition of "contagion"

A disease spread by contact.  examples

The spread or transmission of such a disease.  examples

(figuratively, by extension) The spread of anything likened to a contagious disease.

1. The passing on of manners or behaviour through a closed community or household.  quotations  examples

   Quotations

   • It is true, they were a good-natured and respectable set of servants, who had lived so long in their places that they might be said, by a happy contagion, to have caught kindly feelings from their superiors, and, having assisted in saving the lives of the young ladies, gave them an interest in their pleasures, and a real delight in seeing those fair young faces lighted up with joy.

     1838 (date written), L[etitia] E[lizabeth] L[andon], chapter XIX, in Lady Anne Granard; or, Keeping up Appearances. […], volume I, London: Henry Colburn, […], published 1842, page 242

2. (finance) The spread of (initially small) shocks, which initially affect only a few financial institutions or a particular region of an economy, to other financial sectors and other countries whose economies were previously healthy.  quotations  examples

   Quotations

   • And it was German procrastination that aggravated the Greek crisis and caused the contagion that turned it into an existential crisis for Europe.

     2011, George Soros, Project Syndicate, Germany Must Defend the Euro‎

(finance) A recession or crisis developed in such manner.  examples