pop-up • adj. (of a book or greeting card) containing folded cut-out pictures that rise up to form a three-dimensional scene or figure when the page is turned. ∎  (of an electric toaster) operating so as to push up a piece of toast quickly when it is ready. ∎  Comput. (of a menu or other utility) able to be superimposed on the screen being worked on and suppressed rapidly.• n. 1. a pop-up picture in a book. ∎  a book containing such pictures.2. Baseball see pop¹ (sense 3).3. Comput. a pop-up menu or other utility.

pop-up The relatively uplifted section of a hanging wall which is formed by back thrusting. The structure is bounded by the back thrust and by the major thrust from which the back thrust originated.

pop-up A Web page, often containing advertisements, that appears unexpectedly when a user is browsing.