Source : Webster's Revised Unabridged Dictionary (1913)

Doob grass \Doob" grass`\ [Hind. d?b.] (Bot.)
   A perennial, creeping grass ({Cynodon dactylon}), highly
   prized, in Hindostan, as food for cattle, and acclimated in
   the United States. [Written also {doub grass}.]