Google is officially a verb.

Google Inc.'s eponymous search engine became a sanctioned part of the English language yesterday when "google" — small "g" — earned an entry among the 165,000 or so terms in the 11th edition of the Merriam-Webster Collegiate Dictionary.

The definition: "to use the Google search engine to obtain information ... on the World Wide Web." As in, "Let me google that."

Linguists said google is among the fastest words to enter the lexicon. It reached the pages of the dictionary just five years after its first known reference as a verb in a New York Post article. Usually, it takes 10 to 20 years for a word to enter everyday use.

"That is typical for words used on or about the Web," said John Morse, president and publisher of Merriam-Webster Inc. "Those are words that establish themselves in the language the quickest, because of the power of the Web to propagate words."

The Oxford English Dictionary last month also added the verb Google — but capitalized — to its online dictionary.

Branding experts said such notoriety is hardly a blessing for a corporate trademark. Just ask the makers of Xerox copiers, Band-Aid bandages, Kleenex tissues or Jell-O gelatin.

"I think it's more of a curse," said Rob Frankel, a Los Angeles consultant who has advised the Walt Disney Co., Honda Motor Co. and Sony Corp. on branding issues.

Companies go to extremes to prevent their trademark from falling into "common parlance" — a word that's in everyday use and no longer enjoys legal protection, Frankel said.

Xerox Corp., for instance, ran an ad campaign imploring people not to refer to every photocopying machine as a "Xerox." Attorneys for Johnson & Johnson advised the company to change the jingle for its adhesive bandage from "I am stuck on Band-Aid 'cause Band-Aid's stuck on me" to include the word "brand" after the corporate name — in the interest of safeguarding its trademark.

"It goes, 'I am stuck on Band-Aid brand 'cause Band-Aid's stuck on me,' " said Frankel. "That is why they did that."

Frankel said Google risks losing the value of its corporate trademark if it becomes part of everyday speech.

"It's going to also hurt Google because even though they play everything very, very close to the vest, it is very clear that Google is far more than a search engine," he said. "With Xerox, it's like saying that all Xerox does is copying. That totally disregards all their other incredible pioneering efforts."

Brand names that devolve into common use can lose their trademark status. Think cellophane and aspirin.

Google appreciates the peril. In its 2005 annual report to investors, the Mountain View, Calif., company noted that "there is a risk that the word 'Google' could become so commonly used that it becomes synonymous with the word 'search.' If this happens, we could lose protection for our trademark, which could result in other people using the word 'Google' to refer to their own products."

At least for now, Google offered a measured reaction to the news.

"Defining Google as a verb and as using the Google search engine is appropriate," said company spokesman Steve Langdon.

In its definition of google, Webster's notes that the verb is derived from Google, the trademark for a search engine.

One hundred terms made it into the dictionary's new edition. Among the new entrants: "spyware," defined as "software that is installed in a computer without the user's knowledge and transmits information about the user's computer activities over the Internet" and "mouse potato," a slang term for someone "who spends a great deal of time using a computer."