damper

n. 1 discouraging person or thing. 2 device that reduces shock or noise. 3 metal plate in a flue to control the draught. 4 mus. Pad silencing a piano string.  put a damper on take the vigour or enjoyment out of.

n. That which damps or checks; as: (a) A valve or movable plate in the flue or other part of a stove, furnace, etc., used to check or regulate the draught of air. (b) A contrivance, as in a pianoforte, to deaden vibrations; or, as in other pieces of mechanism, to check some action at a particular time.