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The New Oxford American Dictionary named 'unfriend' -- as in deleting someone as a friend on a social network such as Facebook -- its word of the year in 2009.
Every year a slew of new words are added to the Oxford English Dictionary. This year Bromance, Chillax and Staycation made the list. But for the most cutting edge slang your best bet is the Urban Dictionary. It's an online database where people submit their own entries of new words and phrases from pop culture. They just put out their own list of the best new words of 2010. Site founder, Aaron Peckham, is in the studio.