The economic loss suffered by the society due to the inefficiencies in the market economy. Government policies that establish price floors, ceilings, and taxation regimes are often attributed as the cause for the inability to attain equilibrium and, hence, suffer a deadweight loss.
Diagrams
Originated from/Coined by
Arnold Harberger
Further Reading/ References
https://en.wikipedia.org/wiki/Deadweight_loss
http://www.businessdictionary.com/definition/deadweight-loss.html
https://corporatefinanceinstitute.com/resources/knowledge/economics/deadweight-loss/