Noun

1. 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 (sordine), as in a pianoforte, to deaden vibrations; or, as in other pieces of mechanism, to check some action at a particular time.

   (c) Something that kills the mood

   (d) A device that decreases the oscillations of a system.

   Quotations

   • Nor did Sabrina's presence seem to act as any damper at the modest little festivities. - W. Black

2. Bread made from a basic recipe of flour, water, milk, and salt: but without yeast.

   1827: The farm-men usually bake their flour into flat cakes, which they call dampers, and cook these in the ashes. — Peter Cunningham, Two Years in New South Wales, ii.190. Quoted in G. A. Wilkes, A Dictionary of Australian Colloquialisms, 1978, ISBN 0-424-00034-2.