(Science: botany) A european tree (pyrus aucuparia) related to the apple, but with pinnate leaves and flat corymbs of small white flowers followed by little bright red berries. Called also roan tree, and mountain ash. The name is also applied to two American trees of similar habit (Pyrus Americana, and P. Sambucifolia).
Origin: Cf. Sw. Ronn, Dan. Ronne, Icel. Reynir, and L. Ornus.