To intersperse means to scatter or place things among other things at intervals. When you intersperse jokes throughout a presentation, you're not telling all the jokes at once but spreading them out to keep your audience engaged. When an author intersperses dialogue with description, she alternates between characters talking and details about the setting.

Think of interspersing like adding chocolate chips to cookie dough: you don't dump them all in one spot but distribute them throughout so every bite has a chance of including chocolate. A teacher might intersperse difficult problems with easier ones on a test. A playlist might intersperse upbeat songs with slower ones. A garden might intersperse tall sunflowers among shorter plants.

The word suggests intentional variety and spacing rather than random mixing. When you intersperse something, you're creating a pattern or rhythm that prevents monotony. Notice that we usually say what gets interspersed among or throughout something else, as in “interspersed among the crowd” or “interspersed throughout the book.”