Noun
standard definition (uncountable)
(television) A system that uses a resolution that is not considered to be either high-definition television (720p, 1080i, 1080p, 1440p, 4K UHDTV, and 8K UHD) or enhanced-definition television (EDTV 480p).
Synonym: SD
Coordinate term: high definition
The standard definition of AI is that which we don't understand. Bill Joy