fuliginous[fyoo-LIJ-uh-nus]
(adjective) Fuliginous is a formal adjective that is synonymous with sooty; it describes things related to, containing, or producing soot. It can also describe things that are figuratively sooty—that is, dark or murky, as in "fuliginous soul"—as well as things that are dark or sooty in color, from crystals and insects to the plumage of some bird species.