ˈhärd( ə )nər, ˈhȧd( ə )nə(r noun
( -s )
: one that hardens: as
a.
(1) : a worker who hardens steel objects by heating and quick cooling
(2) : a preliminary alloy added to a melt in order to introduce alloying elements
b.
(1) : a worker who hardens felt
(2) : a machine for hardening felt
c. : a substance added (as to a paint or varnish) to impart greater hardness to the film
d. : a substance (as alum or formaldehyde) used in a gelatin film, emulsion, or processing bath to prevent swelling and softening during processing