See also: Rating

CIMM DEFINITION: The amount of viewing (expressed as a percent) on average, to a program, network, channel, ad, version or time period out of the universe or full population. Can be parsed to the lowest viewing increment whether second, 5 second, minute etc.

2: One of several different kinds of ratings used by Nielsen media research company. It reflects the average size of the audience on a minute-by-minute basis (average size at minute 1, minute 2, minute 3, and so on) throughout the length of a program. (Source: Answers.com)

NOTE – Weighting on averages: averages can be time-weighted or taken as a simple mean. (Source: TIVO)