- The definition of best-case is the most favorable result possible.
An example of best-case is the outcome of an eye surgery being perfect vision.
best-case definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
being the best that can possibly be expected; optimal: a best-case scenario
best-case definition by American Heritage Dictionary
Most favorable; optimum: “the best-case scenario of a mild recession” (Business Week).