Autarky is a practice of economic self-sufficiency, and this means that autarkic nations operate in a state of relative self-reliance. Nations that follow autarky are characterized by independence, self-sufficiency and limited trade with international partners. Autarky became popular among nationalists in the 19th century due to the fear of being encumbered by foreign debts, which were a threat to national sovereignty. The definition of autarky comes from the Greek—autos, meaning "self" and arkein, meaning "to ward off" and "to be strong enough, to suffice." A fully autarkic nation would be a closed economy and lacking any external sources of support, aid or trade.