Definitions of adwords on the Web:

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• A Google® service that accepts advertisements for placement on others' websites. Advertisers pay Google for this service, and Google shares this revenue with the other website owners who publish these ads. (See also AdSense, and Pay-per-Click.)
• Google's pay-per-click (PPC) advertising system. When a search term is entered into the Google search bar, targeted PPC ads appear down the right hand side of the page. For popular search terms, up to three ads also appear above the natural results. ...