helmet vs topper

helmet

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

  • 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 glans penis. 

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

  • A contemptible or stupid person. 

  • The upper part of a chemist's retort. 

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

topper

noun
  • Something that is on top. 

  • A top hat. 

  • A short outer jacket worn by women or children. 

  • The head or chief of an organization. 

  • One who tops steel ingots. 

  • A person or tool that cuts off the top of something. 

  • A pencil sharpener. 

  • A single-handed dinghy, 11 foot (3.6 metres) in length, with only one sail. 

  • A small secondary comic strip seen along with a larger Sunday strip, and usually by the same author. 

  • A three-square float, or file, used by comb-makers. 

  • The student who achieves the highest score in an examination. 

  • Something that exceeds those previous in a series, as a joke or prank. 

  • A soft, relatively thin, piece of padding placed on top of a mattress, or forming the upper layer of a mattress. 

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