popup - Computer Definition
A small window that is displayed on top of the existing windows on screen. A popup window can be used in any application to display new information; however, the term often refers to an advertisement (see popup ad). The window that "pops up" when you select a function from a menu is officially known as a "dialog box." The first popups were DOS terminate and stay resident programs in the 1980s (see TSR). See popup menu.