"Fullscreen" refers to a display mode in which the entire screen is filled with content, making it occupy the whole visible area without any borders or distractions. Full definition
The Omega HD allows you to comfortably view webpages and documents without zooming in in fullscreen on landscape mode. (turbofuture.com)
According to the press release, the final retail version of the Unrated DVD edition offers only a 1.85:1 anamorphic widescreen transfer, whereas the Theatrical Cut holds that and a 1.33:1 fullscreen version on opposite sides of a flipper disc. (dvdizzy.com)
Wild Hearts Can't Be Broken is presented not in anamorphic widescreen like it was in the parts of the world where it was released to DVD first, but in a reformatted 1.33:1 fullscreen transfer as it was for its Disney Movie Club DVD debut last year. (dvdizzy.com)