banner ad n 1. (Marketing) a banner advertising a product 2. (Marketing) an advert along the top of a page of a website 3. (Computer Science) an advert along the top of a page of a website Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014