threshold effect
phenomenon where sudden change occurs in a system when crossing a critical value of some parameter
herd immunity
protection from infectious disease that occurs when a sufficient fraction of a population has become immune (through vaccination or previous infections)
threshold of pain
point at which pain begins to be felt
phase change
transitions between solid, liquid and gaseous states of matter, and, in rare cases, plasma
cliff effect
phenomenon of sudden loss of reception of a digital signal when the level of channel noise exceeds a critical threshold