Introduction a) Definition
According to wikipedia
Economic integration is the unification of economic policies between different states through the partial or full abolition of tariff and non-tariff restrictions on trade taking place among them prior to their integration.
According to business dictionary
The elimination of tariff and nontariff barriers to the flow of goods, services, and factors of production between a group of nations, or different parts of the same nation.
According to investopedia
An economic arrangement between different regions marked by the reduction or elimination of trade barriers and the coordination of monetary and fiscal policies. The aim of economic integration is to reduce costs for both consumers and producers, as well as to increase trade between the countries taking part in the agreement.

b) Meaning of economic intergration
This is meant in turn to lead to lower prices for distributors and consumers with the goal of increasing the level of welfare, while leading to and increase of economic productivity of the states.
The trade stimulation effects intended by means of economic integration are part of the contemporary economic Theory of the Second Best: where, in theory, the best option is free trade, with free competition and no trade barriers whatsoever. Free trade is treated as an idealistic option, and although realized within certain developed states, economic integration has been thought of as the "second best" option for global trade where barriers to full free trade exist.
In economics the word integration was first employed in industrial organisation to refer to combinations of business firms through economic agreements, cartels, concerns, trusts, and mergers—horizontal integration referring to combinations of competitors, vertical integration to combinations of suppliers with customers. In the current sense