Peter Sokolowski, editor at large for Merriam-Webster, said 150 new words appear in this year's update.
"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," Sokolowski said. "We've been tracking words like social media and tweet for years, of course, and now we feel their meanings have stabilized enough to include them in the dictionary."
Other new words included in the update include "bromance," defined as "a close, non-sexual friendship between men," and "cougar," which Merriam-Webster calls "a middle-aged woman seeking a romantic relationship with a younger man."
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