pop-in noun 1pop in verb 1forms 3 noun1 •A performance issue in three-dimensional graphics, causing objects or textures to "pop" suddenly into view as they are loaded, rather than smoothly moving into view. pop in verb1 •(informal) To pay a visit in an impromptu manner.She's popped in a couple of times on her way back from the fields to see if there's any news of the littl'un. — 2009 formspopped in · popping in · pops in