What’s a hipster (hepcat?) to do? Keeping up with the latest slang is at once easier and harder than ever. The number of slang dictionaries is growing, both online and off, not to mention social networking media that invent and discard words, phrases and memes at the speed of broadband. The life of slang is now shorter than ever, say linguists, and what was once a reliable code for identifying members of an in-group or subculture is losing some of its magic.

The Internet “is robbing slang of a lot of its sociolinguistic exclusionary power,” said Robert A. Leonard, a linguistics professor at Hofstra in Hempstead, N.Y., whose slang credentials include being a founding member of the doo-wop group Sha Na Na, formed in the late 1960s. “If you are in a real inside group, you are manufacturing slang so that you can exclude the wannabes.”

And that becomes harder, he added, as the whole world has access to your language.

Part of the problem is that electronic media are making it too easy to compile dictionaries like “U.C.L.A. Slang 6.” While slang dictionaries have been around in one form or another since the 18th century, they now number more than a dozen in print, to say nothing of online resources like UrbanDictionary.com and slangsite.com that are updated hundreds of times daily.

“It used to be that the guys who did all the slang dictionaries would take years just to track it down,” said David Crystal, a linguist who has written more than 30 books. “Now, with the Internet, you just put something up on Facebook and say ‘send me in your slang terms,’ and in a few days you have hundreds of examples and the ability to check it out with other readers.”

Urban Dictionary, which is 10 years old, may be the ultimate example. It is a sprawling, chaotic collection of street talk, all of it user-submitted, giving everyone access to the meaning behind the coded lyrics of someone like Lil Wayne.