Re 'deadweight loss', I wonder what the function of 'weight' is in this
   expression and why 'dead loss' should not suffice. The Oxford English
   Dictionary (1989 edition) gives under the 30th meaning of 'dead':
   30. Said of a charge, expense, loss: Unrelieved, absolute, complete,
   utter; also, of outlay, Unproductive, without returns. dead rent: a fixed
   rent  which remains as a constant and unvarying charge upon a mining
   concession, etc. dead loss: a complete loss; freq. colloq., a person or
   thing that is totally worthless, inefficient, or unsuccessful;  complete
   failure; an utter waste of time. (Cf. quot. 1757.)
   Thus: unproductive, without returns.
   Deadweight Loss is mentioned nowhere, though Deadweight Debt is, under the
   entry 'dead weight,dead-weight':
       4. attrib., as dead-weight debt, a debt not covered by assets, such as
   the greater part of the British National Debt; dead-weight (safety-)valve,
   a safety-valve kept down by a heavy weight.

   Hans Visser