Advertising closes acquisition of's former Chief Executive Jim Lanzone speaks during the Reuters Global Technology, Media and Telecoms Summit in New York, May 14, 2007. REUTERS/Keith Bedford

SAN FRANCISCO (Reuters) -, the Web search unit of IAC/InterActiveCorp, has closed an all-cash deal to acquire Lexico Publishing Group LLC, the owner of popular reference sites and

Lexico of Long Beach, California, was founded in 1995, starting with A year later Lexico introduced and in 2002 began For users who know what they mean but can't recall the term, it also offers a Reverse Dictionary (here). said the deal expands its monthly audience by around 15 million users to 145 million, an increase of 11 percent. Based on March traffic data from comScore Inc, that would make the ninth-largest Web property globally. is the fifth most-visited reference site among U.S. Web users, according to data from online audience measurement site Hitwise Inc. is 39th most visited and ranks 47th.

The influence of within e-commerce conglomerate IAC/InterActiveCorp is growing as New York-based IAC plans to spin off four of its largest businesses and focus on Web media and advertising in coming months.

Terms of the merger were not disclosed. The transaction was originally announced on May 15.

Reporting by Eric Auchard; Editing by Steve Orlofsky