An add-on to a toolbar. It often refers to providing a direct link on a browser toolbar to a search engine or some other site. However, it may refer to any type of toolbar enhancement. See extension and toolbar.
"toolbar extension." YourDictionary, n.d. Web. 17 August 2018. <http://www.yourdictionary.com/toolbar-extension>.
toolbar extension. (n.d.). Retrieved August 17th, 2018, from http://www.yourdictionary.com/toolbar-extension