What is Competition?

Legal Definition
In economics, "competition" is the rivalry among sellers trying to achieve such goals as increasing profits, market share, and sales volume by varying the elements of the marketing mix: price, product, distribution, and promotion. Merriam-Webster defines competition in business as "the effort of two or more parties acting independently to secure the business of a third party by offering the most favorable terms." In his 1776 The Wealth of Nations, Adam Smith described it as the exercise of allocating productive resources to their most highly valued uses and encouraging efficiency, an explanation that quickly found support among liberal economists opposing the monopolistic practices of mercantilism, the dominant economic philosophy of the time. Smith and other classical economists before Cournot were referring to price and non-price rivalry among producers to sell their goods on best terms by bidding of buyers, not necessarily to a large number of sellers nor to a market in final equilibrium.

Later microeconomic theory distinguished between perfect competition and imperfect competition, concluding that perfect competition is Pareto efficient while imperfect competition is not. Competition, according to the theory, causes commercial firms to develop new products, services and technologies, which would give consumers greater selection and better products. The greater selection typically causes lower prices for the products, compared to what the price would be if there was no competition (monopoly) or little competition (oligopoly).

Competition is generally accepted as a necessary condition for the coordination of disparate individuals interests via the market process.

It is generally accepted that competition results in lower prices and a greater number of goods delivered to more people. Less competition is perceived to result in higher prices with a fewer number of—and less innovation in—goods delivered to fewer people. As a result, many governments use competition laws to promote competition and regulate against anti-competitive practices.
-- Wikipedia
Legal Definition
In Scotch practice. The contest among creditors claiming on their respective diligences or creditors claiming on their securities. Bell.
-- Black's Law Dictionary
Legal Definition
(Scotch) A contest between creditors of a bankrupt to establish their rank and preferences.
-- Ballentine's Law Dictionary