Arlington-based Rosetta Stone bought Livemocha, an online community of language learners and teachers, for $8.5 million, the company said Tuesday.

Executives said the acquisition will accelerate Rosetta Stone’s transition toward cloud-based software, which is delivered over the Internet to computers and mobile devices without the hassle of physical CD-ROMs.

“This acquisition will enable both organizations to grow and deliver value faster and more effectively than either could alone,” Rosetta Stone chief executive Steve Swad said in a statement.

Seattle-based Livemocha counts 16 million members from 195 countries who gather on the site to learn and practice foreign languages. Members can leave comments on practice exercises, create lessons, and conduct conversations via text, video or audio.

“The company has pioneered the use of crowd-sourcing to drive content development and social engagement in the realm of language learning,” Rosetta Stone said in a statement.

“Livemocha’s sophisticated and flexible technology platform is expected to be part of the foundation for the next wave of Rosetta Stone solutions,” the statement continued.

Livemocha chief executive Michael Schutzler sent Swad an e-mail titled “alliances” shortly after Swad was named chief executive last year. That sparked an ongoing conversation between the two that resulted in Tuesday’s announcement, Swad said.

Swad said in an interview that Rosetta Stone, with $140 million in cash on its balance sheet, is likely to make additional acquisitions that accelerate its adoption of new technologies.

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