To make gray or to cover with a gray color or substance.
From be- (prefix) + gray (from Old English græg, of uncertain origin but possibly related to Germanic words for 'badger'). This is a straightforward color modification verb.
Gray is one of the few colors where we're not sure of the origin—scholars think it might come from the animal (badger), since ancient peoples sometimes named colors after animals they knew. The 'be-' prefix turns the color name into an action verb.
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