Here’s the simplest possible definition of a story that doesn’t exclude anything important:

How and why[1] The World and/or the People in it change in response to the Protagonist Pursuing a Goal in the face of Conflict.

A reader experiences change in a story by the Shifts in Emotion induced by the perceived distance from the protagonist's goal at each moment.

Assuming a sufficient level of Craft and execution, a reader will be satisfied by a story to the degree it proceeds in a surprising, yet inevitable way (if the aforementioned Shifts in Emotion deliver the desired Dominant Emotions, largely determined by Genre).

1. The how and why of the change is critically important, and interconnected. In a word: Theme. In two words: Genre and Theme.

FROM: THE CONOR BLACK BOOK of STORYTELLING: Volume 1 - Craft