The Collaborative International Dictionary of English v.0.48:

Bel \Bel\ (b[e^]l), n. [Hind., fr. Skr. bilva.]
   A thorny rutaceous tree ([AE]gle marmelos) of India, and
   its aromatic, orange-like fruit; -- called also Bengal
   quince, golden apple, wood apple. The fruit is used
   medicinally, and the rind yields a perfume and a yellow dye.
   [Webster 1913 Suppl.]