No, Cabernet Sauvignon is not a port wine.  The emphatic answer of wine expert and author Jancis Robinson asserts that Cabernet Sauvignon is NOT a port wine.  This is also the answer of British wine expert Oz Clarke, who states that "Cabernet Sauvignon must never be added to Port." However, some wine experts such as British writer and critic Hugh Johnson contend that Cabernet Sauvignon is a correct match with Port. The grape contributes to the aroma, "plushness," and color of port wines.