Simple past tense and past participle of tab. (verb)
Having tabs (the user interface element). (adjective)
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Use "tabbed" in a sentence
"Suffice to say that it covers the essentials with built-in tabbed browsing, mouse-over previews, a customizable search bar, advanced bookmarking tools, simple e-mail and chat integration, mouse gestures, keyboard shortcuts, and drag-and-drop functionality."
"I love the idea of tabbed and category searches -- if the tabs and categories are accurate."
"Then web browsers have a new features which I love called tabbed browsing."