Any substance added to an electrolytic bath to yield a brighter electroplated surface.(noun)
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Use "brightener" in a sentence
"This is the perfect instant face brightener for when the sun is low in the sky and we move to shorter days and long winter nights."
"Terry de Gunzburg is one of the great makeup artists of the past few decades; as makeup director of YSL, she created the legendary Touche Éclat concealer and brightener."
"Always a day-brightener. katy May 4 these rainbow cupcakes are soooooooooooo cute!"