Advertorial noun

An advertisement which is written in the form of an editorial and purports to contain objective information about a product, although actually being limited to the advertiser’s own publicity material. Formed by replacing the first two syllables of editorial with the word advert to make a blend.

The advertorial (both the phenomenon and the word) first appeared in the US as long ago as the sixties, but did not become a common advertising ploy in the UK until the mid eighties. Advertorials came in for some criticism when they started to appear in British newspapers since there was a feeling of dishonesty about them (as deliberately inducing the reader to read them as though they were editorials or features), but they apparently did not contravene fair advertising standards as set out in the British Code of Advertising Practice:

An advertisement should always be so designed and presented that anyone who looks at it can see, without having to study it closely, that it is an advertisement.

In many cases the page on which an advertorial appears is headed advertising or advertisement feature (a more official name for the advertorial), and this is meant to alert the reader to the nature of the article, although the layout of the page often does not. The word advertorial is sometimes used (as in the second example below) without an article to mean this style of advertisement-writing in general rather than an individual example of it.

Yes, advertorials are a pain, just like the advertising supplement pages in Barren’s, but I question whether ‘anyone who bought FNN would have to junk the programming’. Barren’s 24 Apr. 1989, p. 34

This will probably lead to a growth in what the industry calls ‘advertorial’—a mixture of public relations and journalism, or editorial with bias. Sunday Correspondent 22 Apr. 1990, p. 27

Source: The Oxford Dictionary of New Words, 1991.