[bo.nan.za] n [Sp, lit., calm sea, fr. ML bonacia, alter. of L malacia, fr. Gk malakia, lit., softness, fr. malakos soft] (1844) 1: an exceptionally large and rich mineral deposit (as of an ore, precious metal, or petroleum)
2. a: something that is very valuable, profitable, or rewarding "a box-office ~" b: an extremely large amount "expected a ~ of sympathy"