The term 'best-case' is used to describe a situation that is the most favorable or IDEAL. The crossword solutions for this term are IDEAL (5 letters), ROSIEST (7 letters), and OPTIMAL (7 letters). IDEAL refers to something that is perfect or as good as it can be, while ROSIEST implies the most positive outcome and OPTIMAL suggests the best possible result. All three words refer to the same concept of the best-case scenario.