"Flattening the curve" - a term for people avoiding public contact to reduce the otherwise forseeable spike in new cases, slowing the rate of new infections, to the point that the Covid-19 outbreak hospitalized cases don't overwhelm the amount of available hospital beds and respirators to treat them adequately.


"social distancing" - the Covid-19 virus spreads on droplets exhaled, coughed or sneezed by an infected person, so the CDC recommends keeping at least 6 feet away from any other person. Resulting in the mass closing of restaurants, bars, and workplaces, to prevent close contact and further infection.


Unbelievable, on March 9, Wuhan Flu/Covid-19 was a distant thing that was a long way off. How quickly it came among us, and changed our lives overnight.
https://en.wikipedia.org/wiki/2019%E2%80%9320_coronavirus_pandemic


And another term I've heard multiple reporters use over the last 2 weeks regarding the outbreak, calling it
"a black swan".


Here's a Coronavirus glossary of terms.

And
"triage" -a term for rationing limited medical resources in a case where a hospital is overwhelmed with more patients than they have medical facilities or staff to deal with (as cited in Italy).