This year's update of adds more than 150 new words, including some popular among the digerati, including an expanded definition of , the term , and the word . Even m-commerce, which Merriam-Webster defines as "a business transaction conducted using a mobile electronic device," made the cut.

OK, so why these words and not others?

"From the dramatic events of the Arab Spring to the scandal that brought down Congressman Anthony Weiner, tweet is a word that has been part of the story," says Peter Sokolowski, Merriam-Webster's editor at large, in statement.

As for social media and crowdsourcing, Sokolowski says the word-watchers at Merriam-Webster have been tracking those trendy terms for years, and "now we feel their meanings have stabilized enough to include them in the dictionary."

Other pop culture favorites, including bromance ("a close nonsexual friendship between men") and cougar ("a middle-aged woman seeking a romantic relationship with a younger man"), made the Collegiate Dictionary cut as well.