Insatiable means impossible to satisfy, like a hunger or desire that never goes away no matter how much you feed it. Someone with an insatiable appetite for pizza might eat slice after slice and still want more. A reader with an insatiable curiosity about ancient Egypt might devour every book on the subject but still crave learning more.

It describes wanting something in a way that can never truly be fulfilled. An insatiable thirst for knowledge drives scientists to keep investigating even after making discoveries. An insatiable desire for adventure might send an explorer to every corner of the globe, always seeking the next journey.

Sometimes insatiable describes wonderful qualities, like when curiosity or ambition pushes someone to achieve great things. Thomas Edison had an insatiable desire to invent. But it can also describe destructive patterns, like when someone's insatiable need for attention harms their friendships. The word captures that sense of a desire so powerful that nothing quite fills it.