oso-berry|ˈəʊsəʊˌbɛrɪ| [? Amer.Ind.] The blue-black drupe of Nuttallia cerasiformis, a shrub or small tree of western North America. Also the shrub, bearing racemes of greenish-white flowers. 1884Miller Plant-n. 223 Nuttallia cerasiformis, Oso-berry tree, of California.