But″ter‐nut′ (�), n. 1. (Bot.) An American tree (Juglans cinerea) of the Walnut family, and its edible fruit; — so called from the oil contained in the latter. Sometimes called oil nut and white walnut.
2. (Bot.) The nut of the Caryocar butyrosum and C. nuciferum, of S. America; — called also Souari nut.