Definition of blackest:
(adj) :
(of an object) Absorbing all light and reflecting none; dark and hueless.
(adj) :
(of a location or setting) Without light.
(adj) :
(sometimes capitalized) Belonging to or descended from any of various (African, Aboriginal, etc.) ethnic groups which typically have dark pigmentation of the skin. (See usage notes below.)
(adj) :
(US, UK, South Africa) Belonging to or descended from any of various sub-Saharan African ethnic groups which typically have dark pigmentation of the skin.
(adj) :
(card games, of a card) Of the spades or clubs suits.
(adj) :
Bad; evil; ill-omened.