Definitions and terms

Opener window, parent window, main window, first window:

terms often used to describe or to identify the same window. It is the window from which a popup will be created. It is the window on which the user clicked a link which lead to the creation of a requested popup.

Sub-window, child window, secondary window, second window:

terms often used to describe or to identify the same window. It is the popup window which was created.