Source : Webster's Revised Unabridged Dictionary (1913)

Myriameter \Myr"i*a*me`ter\, Myriametre \Myr"i*a*me`tre\, n. [F.
   myriam[`e]tre. See {Myria-}, and {Meter}.]
   A metric measure of length, containing ten thousand meters.
   It is equal to 6.2137 miles.

Source : WordNet®

myriameter
     n : a metric unit of length equal to 10,000 meters [syn: {myriametre},
          {mym}]