Real Dictionary

banana republic
countable noun: Small, poor countries that are politically unstable are sometimes referred to as banana republics.

banana republic in British English
noun: a small country in the tropics, esp. in the Western Hemisphere, whose economy is largely dependent on fruit exports, tourism, and foreign investors
noun: a small country, esp in Central America, that is politically unstable and has an economy dominated by foreign interest, usually dependent on one export, such as bananas