Definitions for "Pop-under"
is a pop-up that loads under a page so that it is only viewable when the current page is closed.
The less obtrusive form of the pop-up window, the pop-under advertisement shows up behind the browser window.
An extra browser window that opens underneath (pops under) a web page you visit. Pop-unders are usually advertisements.
an additional Service to those already provided under your existing MIVA contract