“Availability” — short for “availability heuristic or availability bias, a pervasive mental shortcut whereby the perceived likelihood of any given event is tied to the ease with which its occurrence can be brought to mind”. “Cascade” — short for “social cascades through which expressed perceptions trigger chains of individual responses that make these perceptions appear increasingly plausible through their rising availability in public discourse”. An availability cascade is what happens when a social cascade rips through a population based on a more or less arbitrary topic — whatever topic happens to be in front of people when the cascade starts.