1.
A pop-up book, usually a children’s book, has pictures that stand up when you open the pages.
ADJ : ADJ n
2.
A pop-up toaster has a mechanism that pushes slices of bread up when they are toasted.
ADJ : ADJ n
3.
On a computer screen, a pop-up menu or advertisement is a small window containing a menu or advertisement that appears on the screen when you perform particular operations. ( COMPUTING )
...a program for stopping pop-up ads.
ADJ : ADJ n