The social networking website Facebook has made it into the dictionary, it was announced today.

The site's soaring popularity has won its inclusion in the 2008 edition of the Collins English Dictionary, according to a Collins spokeswoman.

Editors have defined the term as both a trademarked noun referring to "a popular social networking website", and as a verb, meaning "to search for (a person's profile) on the Facebook website".

And in an acknowledgement of how people may reveal potentially embarrassing information on the site, the dictionary gives as an example of the word's usage: "I thought one of the interviewees was perfect for the job, until I Facebooked him."

According to Collins, the term "Facebook" occurs 10 times more frequently in recent updates to its dictionary databases than it does in sources overall - which prompted editors to add the term.

The spokeswoman said: "'Facebook' has been the phenomenon of 2007. Though social networking has been around for several years, this year has seen it break into the mainstream, with 200,000 signing up every day."

Editors have also noted a variety of words relating to Facebook, with the dictionary giving fresh meaning to the word "pimp".

It explains that to "pimp (one's profile)" is "to make one's profile page on a social networking site appear more attractive by adding graphics, video, music, etc".

In addition, the mysterious "poke" function on Facebook is finally pinned down.

Facebook itself says of the function: "We thought it would be cool to have a feature without any specific purpose ... we encourage you to come up with your own meanings."

But the dictionary explains the Facebook "poke" as "to use the "poke" facility of the Facebook website to attract the attention of (another user)".

Other words newly recognised by the dictionary are "subprime" and "green-collar".

Following the Northern Rock crisis, the word "subprime" shot into newspapers, the spokeswoman said.  But dictionary editors found that the term usually refers to borrowers rather than the terms of the loans themselves.

It is defined as both an adjective referring to a loan "made to a borrower with a poor credit rating, typically at a high rate of interest", and as a noun, meaning "a high-interest loan made to a borrower with a poor credit rating".

Related words include "credit crunch", or "a period during which there is a sudden reduction in the availability of credit from banks and other lenders".

And the dramatic-sounding "ninja loan" is defined as "a type of high-risk loan issued to borrowers with no income, no job, and no assets", while a "bank run or a run on a bank" is explained as "a rush to withdraw funds from a bank by customers fearing the bank's imminent insolvency".

Meanwhile the growth of the green economy in 2007 saw a rise in the 'green-collar' employee, according to Collins.

The dictionary defines the term as an adjective "of, relating to, or designating workers involved in environmental protection, or employed by companies that have protection of the environment as a stated aim".