Final answer:
The term for the turning point affecting the story's outcome for the main character is the climax, which represents the highest point of tension and conflict.
Step-by-step explanation:
The term used to describe a turning point for the main character in a story, where something happens that will significantly affect the outcome, is known as the climax.
The climax is typically the moment of greatest tension or conflict in the narrative, and it is where the protagonist faces a crucial situation that leads to a resolution of the main conflict. This turning point can take various forms, such as an important decision, a revelation, or a confrontation between characters.
Often, the climax can be accompanied by sub-climaxes or minor turning points that build suspense in the storyline. Following the climax is the falling action, where events begin to wind down and lead to the story's conclusion.