A state of deprivation means something is missing, and the situation is serious. If you're suffering from sleep deprivation, you haven't slept in a long time.
If you know the word deprive — meaning to keep something away from someone — then you’re close to knowing what deprivation means. It describes the state of not having something. Poor people experience a lot of deprivation: poverty keeps them from having enough food or shelter. Plants experiencing water deprivation will shrivel up and die. If you’re grounded your parents might impose video game deprivation, although this word is usually reserved for when you’re lacking something really serious.