crabapple (Noun) — Any of numerous varieties of crab apples cultivated for their small acidic (usually bright red) fruit used for preserves or as ornamentals for their blossoms.
crabapple (Noun) — Any of numerous wild apple trees usually with small acidic fruit.
crabapple (Noun) — Small sour apple; suitable for preserving. ex. "crabapples make a tangy jelly"