title_body: What is opposite of "burzum", "darkness", in Tolkien's Black Speech? I'm aware that burzum means darkness in The Black Speech.
  
  Do we know what the opposite is? How is lightness written?
upvoted_answer: As @Darkgamma says, we don't know.  The closest we have would probably be ghâsh, which means fire, and one could probably guess that the characteristic of being fire-like would be something like ghâshum, but there is no empirical evidence for that, except that the suffix -um seems to mean -ness, as in burz- (meaning dark) + -um (meaning -ness), put together to form burzum.
  
  That said, ghâshum would literally mean "the characteristic of being like fire," not literally "lightness."