The Collaborative International Dictionary of English v.0.48:

Myriagram \Myr"i*a*gram\, Myriagramme \Myr"i*a*gramme\, n. [F.
   myriagramme. See Myria-, and 3d Gram.]
   A metric weight, consisting of ten thousand grams or ten
   kilograms. It is equal to 22.046 lbs. avoirdupois.
   [1913 Webster] Myrialiter

WordNet (r) 3.0 (2006):

myriagram
    n 1: one ten thousandth of a centner [syn: myriagram, myg]