A phonestheme, of course. James Harbeck of The Week explains why so many villains’ names include the element “mor.” Along the way, you’ll learn that a phonestheme is “a part of a word that tends to carry a certain connotation not because of etymology or formal definition but just by association.” So, “mor” words tend to suggest darkness, evil, or death. Words that start with “sn” tend to have to do with the nose (sneeze, snore, sniffle, etc.). Sometimes, words even shift their pronunciation in the direction of the phonestheme once it has reached a certain critical mass. Mordred from the Arthurian legends was originally Medraut.
Keep all this in mind the next time you face down a pack of hungry Morlocks, or decide to take a stroll into Mordor.