Darkener n. : One who, or that which, darkens.

Example:
Can black coffee really be used as a natural hair Darkener?

Taxonomy
Merriam-Webster Online Dictionary, Dictionary, webster, darkener, där, Word Games, Webster Online Dictionary with audio pronunciations, thesaurus, glossary, english, language, ESL, Search, Inflected, ened, 14th century, intransitive verb, skies.

Defination from the web:
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