deadweight loss

deadweight loss definition from Answers.com:

1. Investment dictionary

deadweight loss: " The costs to society created by an inefficiency in the market.
Investopedia Says:
Mainly used in economics, the term 'deadweight loss' can be applied to any deficiency due to an inefficient allocation of resources. Lost production due to inaccurate forecasting for labor is an example of a deadweight loss."

2. Wikipedia: deadweight loss

Deadweight loss created by a binding price ceiling. Producer surplus is necessarily decreased, while consumer surplus may or may not increase; however the decrease in producer surplus must be greater than the increase (if any) in consumer surplus.
In economics, a deadweight loss (also known as excess burden) is a loss of economic efficiency that can occur when equilibrium for a good or service is not Pareto optimal. In other words, either people who would have more marginal benefit than marginal cost are not buying the good or service or people who would have more marginal cost than marginal benefit are buying the product.
Causes of deadweight loss can include monopoly pricing (see artificial scarcity), externalities, taxes or subsidies (Case and Fair, 1999: 442), and binding price ceilings or floors. The term deadweight loss may also be referred to as the "excess burden of monopoly" or the "excess burden of taxation".