"Unfriend" has been named the word of the year by the New Oxford American Dictionary, chosen from a list of finalists with a tech-savvy bent.
Unfriend was defined as a verb that means to remove someone as a "friend" on a social networking site such as Facebook.
"It has both currency and potential longevity," said Christine Lindberg, senior lexicographer for Oxford's U.S. dictionary program, in a statement.
"In the online social networking context, its meaning is understood, so its adoption as a modern verb form makes this an interesting choice for Word of the Year."
Other words deemed finalists for 2009 by the dictionary's publisher, Britain's Oxford University Press, came from other technological trends, the economy, and political and current affairs.
In technology, there was "hashtag," which is the hash sign added to a word or phrase that lets Twitter users search for tweets similarly tagged; "intexticated" for when people are distracted by texting while driving, and "sexting," which is the sending of sexually explicit SMSes and pictures by cellphone.
Finalists from the economy included "freemium," meaning a business model in which some basic services are provided for free, and "funemployed," referring to people taking advantage of newly unemployed status to have fun or pursue other interests.
In the political and current affairs section, finalists included "birther," meaning conspiracy theorists challenging President Barack Obama's U.S. birth certificate, and "choice mom," a person who chooses to be a single mother.
Novelty words making the shortlist were "deleb," meaning a dead celebrity, and "tramp stamp," referring to a tattoo on the lower back, usually on a woman.