Source : Webster's Revised Unabridged Dictionary (1913)

Rattler \Rat"tler\, n.
   One who, or that which, rattles.

Source : WordNet®

rattler
     n 1: pit viper with horny segments at the end of the tail that
          rattle when shaken [syn: {rattlesnake}]
     2: a railroad train consisting of freight cars [syn: {freight
        train}]