General Definition: 1. A flat surface the moves sideways in front of another flat surface or any thing or any action that can be easily associated with this in a given context, such as a sliding-door or a photographic slide. As a Noun: 1. A door which opens by sliding sideways rather than by swinging open. English = sliding door. 2. A small piece of photographic film which can be projected onto a screen so that you can see the picture. English = slide. As a Verb or Adjective: 1. Of a sliding door, to close. 2. Of a photographic slide, to be moved into position.