breaststrap vs helmet

breaststrap

noun
  • A piece of horse tack for preventing the saddle from slipping backwards. 

  • An oblong application supporting the mammaries of a human female 

helmet

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

  • 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 contemptible or stupid person. 

  • The upper part of a chemist's retort. 

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

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