1) American crime novel 
[v] - obliterate or extinguish, of lights 2. [v] - darken completely 3. [v] - suppress by censorship
verb darken completely; `The dining room blackened out` verb suppress by censorship as for political reasons; `parts of the newspaper article were blacked out`
Also referred to as black patch; a piece of masking material which is used in layout to mask an area leaving a window into which another element can be stripped.