regenerator

\\rēˈjenəˌrād.ə(r), -ātə-\ noun

Etymology: Late Latin, from Latin regeneratus (past participle of regenerare to regenerate) + -or

1. : one that regenerates

2. : a heavy swinging counterpoise or other balancing device for a mine pump rod to permit a higher engine speed

3. : a hypothetical body (as used with a reversible engine operating on a Stirling cycle) that stores heat from the working substance of an engine so that each part of the body and the contiguous gas or vapor have the same temperature, each increment of heat is maintained at the temperature at which it was received, and the stored heat is returned to the working substance by the reversal of the process

4. : a device used especially with hot-air engines or gas-burning furnaces in which the incoming air or gas is heated by contact with masses (as of iron, brick) previously heated by the outgoing hot air or gas or by being passed through a pipe or pipes heated by a flow of the hot air or gas escaping in the opposite direction — compare heat exchanger