The Collaborative International Dictionary of English v.0.48:

Decagram \Dec"a*gram\, Decagramme \Dec"a*gramme\, n. [F.
   d['e]cagramme; Gr. de`ka ten + F. gramme. See Gram.]
   A mass in the metric system equal to ten grams, and equal to
   about 154.32 grains avoirdupois. See 3rd Gram.
   [1913 Webster]

WordNet (r) 3.0 (2006):

decagram
    n 1: 10 grams [syn: dekagram, decagram, dkg, dag]