From Longman Dictionary of Contemporary Englishcrab appleˈcrab ˌapple noun [countable] DFa small sour apple, or the tree it grows on
Examples from the Corpus
crab apple• I picked one and threw it at a crab apple tree.• And then a crab apple flew in and bounced a few feet from Pinky.• The result: plenty of fresh produce for the kitchen and such delights as crab apple and quince jellies and pickled walnuts.• We've planted every kind of native tree you could think of in a hedge, including crab apple and wayfarer tree.Origin crab apple (1400-1500) Perhaps from → CRAB 