Shooting image without recording sound. Lots of colorful stories have evolved in an attempt to explain the origin of this curious term: one story suggests that a famous Hollywood director from Germany used to say mitt-out-sound while other explanations are technically oriented, suggesting it means minus optical stripe (since some old sound recording systems recorded the audio signal as visual variations on light sensitive film), or it could simply mean motion omit sound, but no one really knows the origin of this term, or do they?