The spray produced when people cough or sneeze, and which can spread diseases like COVID-19.

The spray produced by sneezing, coughing or even talking. "Have you ever seen that kind of classic picture of a kid coughing and the amount of droplets coming out?" quoting Melissa Nolan. "It's aerosolized particles from your lungs being respired" - that is, breathed out.

Droplets can spread disease when an infected person coughs or sneezes - and the spray lands on a nearby person's mouth, nose or eyes. It can also spread when a person touches a body part or a surface with infected droplets, then touches their face.