Poustinia is the Russian word for “desert.” It is also used in Russian Orthodoxy to refer to a place where a solitary goes to seek ongoing silence and solitude before God. A solitary monk who lives in a poustinia (usually a simple, small structure) is called a poustinik. In Russia, a poustinik typically lives on the outskirts of a town and is available for the townspeople to come, meet, and ask for direction or specific help – even for things like lending a hand in the field during harvest season. The poustinik is a spiritual director of sorts, and also makes him or herself available for the practical needs of the community.
Catherine Doherty, founder of Madonna House in Canada, wrote a classic book about the concept of poustinia, simply called Poustinia.