Cross-sell is a marketing term for the practice of suggesting related products or services to a customer who is considering buying something. If you're buying a book on Amazon.com, for example, you may be shown a list of books similar to the one you've chosen or books purchased by other customers that bought the same book you did. A search on a company's Web site for bed linens might also bring up listings of matching draperies. The most ubiquitous example of cross-sell is likely the oft-spoken fast food phrase: "Would you like fries with that?"
A similar practice, up-sell, involves suggesting more expensive items to a customer making a purchase.