Sof"ten*er (?), n.
One who, or that which, softens.
[Written also, less properly, softner.]
<-- Water softener, a device which exchanges sodium ions for polyvalent metal cations in water, thus converting the "hard" mineral-containing water into "soft" water. This treatment renders the water more usable for washing, as the polyvalent cations interfere with the detergent action of soaps. -->
© Webster 1913.