Final answer:
The bottom of the ninth inning refers to the final half-inning of a baseball game played by the team that is behind in score.
Step-by-step explanation:
In the context of baseball, the phrase 'bottom of the ninth inning' refers to the final half-inning of the game, played by the team that is behind in score. It is their last chance to score runs and potentially win the game. The 'bottom' part indicates that it is the home team's turn to bat. The 'ninth inning' signifies that it is the last inning in a regulation game, as baseball games typically consist of nine innings.