DuckCorp Dico

Found one definition

1.                 From The Collaborative International Dictionary of English v.0.48:
                   
   
   
                   
                     
   adust \a*dust"\ ([a^]*d[u^]st"), a. [L. adustus, p. p. of
      adurere: cf. F. aduste.]
      1. Inflamed or scorched; dried or darkened by heat. "The
         Libyan air adust." --Milton. --AS
         [1913 Webster]
      2. Sunburnt. [archaic] --AS
         [1913 Webster]
               A tall, thin man, of an adust complexion. --Sir W.
                                                     Scott.
         [1913 Webster]
      3. (Med.) Looking or acting depressed; atrabilious; gloomy.
         [archaic] --AS
         [1913 Webster]