Deadweight loss
Etymology
The term joins "deadweight," an old English shipping and engineering word for inert, non-productive load carried by a vessel, with the economic notion of "loss." It entered welfare economics through the surplus analysis developed after Alfred Marshall in the late nineteenth century, and the classic triangular diagram is often tied to Arnold Harberger, so the shape is sometimes called the "Harberger triangle." The image is of weight that yields nothing back — waste that no party captures.
noun · /DED-wayt laws/
The value that simply vanishes — benefiting no one — when a tax, subsidy, monopoly, or other friction prevents trades that both sides would have wanted to make.
What it names
The difference between a transfer, where money merely moves from one pocket to another, and a genuine waste where a mutually beneficial deal never happens at all — a distinction that reframes most arguments about regulation and pricing.
Example
The ticket scalping ban feels just, but by blocking sales between willing buyers and sellers it mostly creates deadweight loss — empty seats no one gains from.
Related idea
A transfer moves surplus from one party to another and nets to zero for society; deadweight loss is surplus that no one gets, distinct also from opportunity cost, which is the value of the road not taken.