The Collaborative International Dictionary of English v.0.48:

Babul \Ba*bul"\, Babool \Ba*bool"\, n. [See Bablah.] (Bot.)
   Any one of several species of Acacia, esp. Acacia
   Arabica, which yelds a gum used as a substitute for true gum
   arabic.
   [1913 Webster]

         In place of Putney's golden gorse
         The sickly babul blooms.                 --Kipling.
   [Webster 1913 Suppl.]