a figure used in comparing /evaluating the relative cost efficiency of media; the advertising cost of reaching 1,000 readers. (e.g. ABC magazine's Page 4C cost = $25,000. It reaches 1,000,000 Women, age 35-44. It's CPM for Women 35-44 is: $25,000/1,000,000 = $25).
The cost of advertising per thousand potential customers reached by a given publication, broadcast, or outdoor advertisement. This figure is often used in media planning.