popup

Definitions of pop up in various dictionaries:

noun - a book (usually for children) that contains one or more pages such that a three-dimensional structure rises up when a page is opened

noun - a short high fly ball

verb - appear suddenly or unexpectedly

Emerging quickly from a recessed or concealed position when activated: pop-up gun emplacements.

Rising to form a three-dimensional structure when a page is opened: pop-up illustrations in a children’s book.

A device or an illustration that pops up.

See pop fly.

POP UP - appear suddenly or unexpectedly; "The farm popped into view as we turned the corner"; "He suddenly popped up out of nowhere"