1. mysterious Strictly, that which is black is absolutely destitute of color; that which is dark is absolutely destitute of light. In common speech, however, a coat is black, tho not optically colorless; the Synonyms: dark, black, dusky, mysterious, sable, somber, dim, gloomy, obscure, shadowy, swart, dismal, murky, opaque, shady, swarthy Antonyms: bright, crystalline, glowing, lucid, shining, brilliant, dazzling, illumined, luminous, transparent, clear, gleaming, light, radiant, white