noun
or ton·ca bean ˈtäŋkə- ; or ton·ga bean -ŋgə- ; also ton·qua bean -ŋkə-
Etymology: probably from Tupi tonka
: the seed of any of several plants of the genus Dipteryx (especially D. odorata and D. oppositifolia ) that has a pleasant odor due to the presence of coumarin and is used in the manufacture of coumarin, in perfumes, as a flavor for tobacco, and in making artificial vanilla extracts ; also : a plant whose seed is a tonka bean