an ad that runs in a separate ad window associated with a concurrently displayed banner. In normal practice, the content and banner are rendered first and the daughter window appears thereafter.

a new browser window, usually smaller than the existing browser window, that pops up when the user clicks on the banner

A smaller browser window that pops up when you hit a Web page. Daughter windows are used to present ads, news, special promotions and site indexes. They first became popular with adult websites, but can now be found everywhere.

see Superstitial