widescreen

Short definition from Wiktionary

Noun

1. 1
   A screen with a wider aspect ratio than the ordinary 35-millimeter frame, making more effective use of the human field of view and producing a more immersive view experience.

Adjective

1. 1
   Filmed in a greater aspect ratio than the 1.33:1 or 1.37:1 aspect ratio.
2. 2
   Presented in the original aspect ratio; presented in letterbox orientation.