sour cherry

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A widely cultivated deciduous shrub or small tree (Prunus cerasus) of the rose family, native to Eurasia, having white flowers and tart red fruit.
• noun The edible fruit of this plant.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun a species of Prunus in the subgenus Cerasus (cherries), native to much of Europe and southwest Asia, Prunus cerasus
• noun the fruit of this tree

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun acid cherries used for pies and preserves
• noun rather small Eurasian tree producing red to black acid edible fruit
• noun Australian tree with sour red fruit