Concentration of exports on a narrow range of categories of goods and services, or a narrow range of countries. The higher its degree of export concentration, the more liable are a country’s balance of trade and national income to disruption by fluctuations in the sectors of the world degree of risk. Export concentration is generally highest in some of the oil-exporting countries, and some of the world’s smaller primary commodity exporters. It is generally low in industrial countries.
Reference: Oxford Press Dictonary of Economics, 5th edt.