Pulverize is a cooking technique that turns something into a very fine powder. It can be done manually or with a machine, by crushing, grinding or pounding.
Pulverizing a food item allows the taste of things such as spices to be more evenly distributed throughout a dish; it also allows items to be stored in far less space than they take in their unpulverized state. The downside to the storage space bonus is that the more of the item exposed to the air, the shorter its shelf life is.