From IRC Improv Wiki
A scene is the place where a series of fictional events occur or occurred on stage.
"A scene is a sequence where a character or characters engage in some sort of action and/or dialogue. Scenes should have a beginning, middle and end (a mini-story arc), and should focus around a definite point of tension that moves the story forward."
- Teach Yourself How to Write a Blockbuster, by Lee Weatherly and Helen Corner (pg 40, 2006 edition)
"By “scene” we mean here all that is included in an unbroken flow of action from one incident in time to another […] The action within a scene is ‘unbroken’ in the sense that it does not include a major time lapse or a leap from one setting to another – though the characters may, of course, walk or ride from one place to another without breaking the scene, the camera, so to speak, dollying after them."
- The Art of Fiction: Notes on Craft for Young Writers, John Gardner (pg 59, 1991 edition)
"For me, a scene is a unit of story in which something changes. It has a beginning, a middle, and an end, and at the end something is different than it was at the beginning. It may be a character or a situation, or just our understanding of a character or a situation, but whatever it is, it’s changed when the scene is over."
- What’s a Scene (And What’s A Chapter?), Timothy Hallinan, TimothyHallinan.com