Source : Webster's Revised Unabridged Dictionary (1913)

Decameter \Dec"a*me`ter\, Decametre \Dec"a*me`tre\, n. [F.
   d['e]cam[`e]tre; Gr. de`ka ten + m[`e]tre. See {Meter}.]
   A measure of length in the metric system; ten meters, equal
   to about 393.7 inches.

Source : WordNet®

decametre
     n : a metric unit of length equal to ten meters [syn: {decameter},
          {dekameter}, {dekametre}, {dam}, {dkm}]