best/worst-case scenario

The  best  or  worst  possible  outcome  for  a situation. These clichés use scenario in the sense of an imagined situation or sequence of events, a usage that has become common since about 1960. For example, “In the best-case scenario, Dad set off the burglar alarm acciden- tally,” or “It isn’t just that the price is higher, but none are left even at that price—that’s   the   worst-case   scenario.” An   amusing   how-to   manual   by David  Borgenicht  and  Joshua  Piven, The  Worst-Case  Scenario  Survival  Hand- book  (1999), probes  improbable  mishaps  and  emergencies, such  as  how  to escape quicksand or how to land a pilotless airplane.