the black seed of a South American tree, which has a vanilla-like fragrance. The dried beans are cured in rum or other alcohol and then used in perfumery and for scenting and flavouring tobacco, ice cream, and other products.
The tree is Dipteryx odorata, family Leguminosae
late 18th century: tonka, a local word in Guyana
tonka bean in other Oxford dictionaries
Definition of tonka bean in the US English dictionary