Definitions for "Gross rating point"
The total number of impressions delivered by a media schedule expressed as a percentage of a market population. In outdoor a GRP level is sometimes referred to as a showing, and is measured on a daily basis.
The sum of the average quarter-hour ratings for all the commercial positions in a program (or series of availabilities); used to estimate the number of ratings points delivered by an advertising "buy."
3/4– A unit of measurement of audience size. It is used to measure the exposure to one or more programs or commercials, without regard to multiple exposures of the same advertising to individuals. One GRP = 1% of TV households.