Source : Webster's Revised Unabridged Dictionary (1913)

Tumbleweed \Tum"ble*weed`\, n. (Bot.)
   Any plant which habitually breaks away from its roots in the
   autumn, and is driven by the wind, as a light, rolling mass,
   over the fields and prairies; as witch grass, wild indigo,
   {Amarantus albus}, etc.