Should 'bromance' really be in the dictionary? Merriam-Webster thinks so.

“English is a living language,” says no less an authority than Sarah Palin, who has coined a few words herself. So if you refudiate that notion, then you're probably not happy with Merriam-Webster right now.

The new Merriam-Webster Collegiate Dictionary has added 150 words in its latest 2011 edition, including, “bromance” (a close, nonsexual friendship between men), and “cougar” (middle-aged woman seeking a romantic relationship with a younger man).

Here's a couple more: “fist bump” (touching knuckles lightly with another person in lieu of a handshake), and “parkour” (a new sport which combines running, climbing, and leaping over environmental obstacles).

Who cares? Who should care?

It turns out dictionaries reflect not only which words are born each year, but which words die, as well. And since space remains constant – for collegiate editions, anyway – keeping track of what words come in and go out gives us a sort of compendium of the national consciousness.

“It's useful for speakers of any language to see that the word stock is always changing – new words are steadily adopted by users, and some old words drop out, too,” says Laurel Smith Stvan, associate professor of linguistics at the University of Texas at Arlington, in an e-mail. "Some of them will likely drop from use before others, of course.”

What does it say about our preoccupations and attitudes, one might ask, that the following words – not to be found in the 1969 American Heritage Dictionary – elbowed their way into the first major revision, published in 1982: upmanship, uptempo, fed up, breaking point, railroading, group therapy, last ditch, last minute, last straw.

It's harder to find the ones they replaced, but four that disappeared are cartwright, carpenter moth, bread line, and the Marx Brothers.

“There’s always a clash between something that the people say all the time, and then the elite who decide when it goes into the dictionary," says Bryan Crable, founding director of Villanova University’s Waterhouse Family Institute for the Study of Communication and Society. "Just because a lot of people use a word, does that mean it should be enshrined as an official part of the language? Dictionary people get into some very serious arguments about this.”

Peter Sokolowski, Merriam-Webster's editor at large, explains why his dictionary has chosen the 150 new words.

"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," said Mr. Sokolowski, according to Reuters. "Now we feel [these words'] meanings have stabilized enough to include them in the dictionary."

New words often don't describe new things, they define new aspects of human relationships. "We need words to show how we interact,” says Professor Crable. “Bromance" he says, “is a convenient shortcut to identifying a situation between two men in a way that ‘friend’ or ‘lover’ doesn’t."

Merriam-Webster’s latest dictionary now reflects evolving child-parent relationships with the term, “helicopter parent” (a parent who is overly involved in the life of his or her child), and “boomerang child” (a young adult who returns to live at his or her family home, especially for financial reasons).

Some custodians of English blanch at such terms gaining legitimacy. "How long before they get around to including all of the text-speak non-words? The dictionary should be reserved for standard spoken English," says Jim Farrelly, an English professor at the University of Dayton in Ohio, in an e-mail. "Let the online dictionaries keep a record of the culture-bound words."

Stayed tuned on the word, “refudiate.” Palin made the remark in a July 2010 tweet – the common mixing of two words known as “malapropism” – and defended herself later by saying, “English is a living language.”

She’s right about that, say linguists. But future dictionary-makers will have to weigh the word’s staying power.

Recent polls show it might have more longevity than Palin herself.