1080i
Definition:
The "1080" part of 1080i describes the number of vertical lines that make up a television or video signal. Most television or video signals are rated at 480, 720 or 1080. The more vertical lines that make up the picture, the crisper or higher definition the picture. The "i" following 1080 indicates that the video display is constructed using an interlaced method.
Some television stations broadcast their high definition signals in a 1080i format.