ro·silla \rōˈzilə, -ˈsilə, -ˈsē(y)ə\noun (-s) Etymology: American Spanish 1.: a sneezeweed (Helenium puberulum) of southern California 2.: a shrub or small tree (Eysenhardtia polystachya) of the family Leguminosae of Arizona and adjacent Mexico with small white flowers in long racemes — see nephritic wood