Definition of "Common"

Common¹

proper noun
plural Commons
1. A surname.

Common²

proper noun
1. (science fiction, fantasy) Denoting the name of a universal language in various works.
  Quotations
  Both princesses spoke Common well enough. Soon we realized that they knew each other.
  2011, Elizabeth Moon, Kings of the North, New York, N.Y.: Ballantine Books, page 395