MATTED WIDESCREEN (FLAT): 35MM - 1.85:1
When you watch a movie that was filmed in a "flat" or "spherical" method, that is with no horizontal ("anamorphic") compression, or in a format called Super35, the top and bottom are matted out to provide the aspect ratio that the filmmakers intended. This is known as "soft matting". Most matted movies are matted to a 1.85:1 aspect ratio.
The compilation above is an example from the classic comedy “A Fish Called Wanda”. In this scene, John Cleese is supposed to be naked when suddenly (and unexpectedly) a family walks in. The picture on the left shows the scene in its intended, matted aspect ratio of 1.85:1 and does indeed give the impression that he is naked. The picture on the right shows the same scene in a "full frame" format where the mattes are removed. As you can see, he's actually wearing shorts, thus dramatically reducing (if not eliminating) the intended comedic effect of the scene.
SOURCES:
http://www.widescreen.org/widescreen_matted.shtml