crab apple vs crabapple

crab apple

crabapple

noun
  • An unpleasant person; a person who is crabby. 

  • The fruit of this tree. 

  • Any of the wild species of apple tree, genus Malus, which generally yield small, bitter fruit (in comparison to domestic apples, Malus domestica). 

How often have the words crab apple and crabapple occurred in a corpus of books? (source: Google Ngram Viewer )