What do abbreviations in movie scripts stand for? For example,
These abbreviations represent the type of scene and the area where it's being filmed.
EXT. => Exterior
INT. => Interior
O.S. => Abbreviation for Off Screen, denoting that the speaker is not resident within the scene.
V.O. => Abbreviation for Voice Over, denoting that the speaker is narrating the action onscreen.
You can find more abbreviations on the linked pages.