I found the most unhelpful set of definitions/equivalents yet in this New Great Russian-English Dictionary entry: "опалённый ppp of опалить; adust; sphacelate, deustate." Now, if you look further down the page you'll see that опалить means 'to singe,' and therefore its past passive participle must mean 'singed,' but the first thing your eye lights on is that forbidding sequence "adust; sphacelate, deustate." There may be a non-empty set of "English-speakers to whom those words mean something," but I have my doubts whether it overlaps with the set of "people who consult the New Great Russian-English Dictionary." Just for kicks, I'll explain them here.
You might guess that adust means 'dusty,' and in fact such a word exists, but this is a different adust, from Latin adūstus 'burnt, scorched; dusky, swarthy, (of colour) dark,' first used in English (c. 1400) to mean "Designating any of the humours of the body when considered to be abnormally concentrated and dark in colour, and associated with a pathological state of hotness and dryness of the body" ("Of the four humours, choler appears to have been the most often described as adust"); later senses were "having a melancholy character or appearance; gloomy; sallow," " Burnt, scorched; desiccated by exposure to strong heat; parched," and "Of or designating a dark brown colour, as if scorched; (of a person) dark-skinned, tanned." All are rare and/or obsolete.
The OED entry for sphacelate has not been updated since 1914; the adjective is called Obs. rare and defined as "Sphacelated," and only two cites are given (1634 T. Johnson Wks. xxvi. xxxi. 1064 "Exhalations, lifted or raised up from any part which is gangrenate or sphacelate"; 1785 T. Martyn Lett. Elements Bot. xxvi. 392 "Having a cylindric..calyx, with the scales sphacelate or seeming mortified at top"); sphacelated means "Mortified, gangrened" and has a fair sprinkling of cites from 1639 (J. Woodall Surgeons Mate 387 "They used to take of the Sphacelated member") to 1877 (F. T. Roberts Handbk. Med. I. 393 "The sphacelated portion is expelled"). Both are from the verb sphacelate "To affect with sphacelus; to cause to gangrene or mortify" or "To become gangrenous or mortified," from a medieval or modern Latin borrowing of Greek σϕάκελος 'gangrene.'
As for deustate, it clearly has the same Latin ūst- root as adust, but I regret to say it is unknown to the OED; Google Books turns it up in A Glossary of Mycology (1971) by Walter Snell and Esther A. Dick: "deustate, deustous. As if scorched. [< L. deurere to burn up.]" How the compilers of the New Great Russian-English Dictionary got hold of it, god only knows.