helmet vs whacker

helmet

noun
  • A contemptible or stupid person. 

  • The hood-shaped upper sepal or petal of some flowers, as of the monkshood or the snapdragon. 

  • A naked shield or protuberance on the top or fore part of the head of a bird. 

  • The feature above a shield on a coat of arms. 

  • The glans penis. 

  • A hard, protective head covering, typically part of armour. 

  • The upper part of a chemist's retort. 

verb
  • To cover with, or as if with, a helmet. 

whacker

noun
  • One who, or something which, whacks. 

  • Synonym of whopper (“an outrageous or blatant lie”) 

  • Synonym of whopper (“anything large”) 

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