achene vs hull

achene

noun
  • A small, dry, indehiscent fruit, containing a single seed, as in the buttercup. 

hull

noun
  • The outer covering of a fruit or seed. 

  • Any covering. 

  • The body or frame of a vessel, such as a ship or plane. 

  • The smallest set that possesses a particular property (such as convexity) and contains every point of A; slightly more formally, the intersection of all sets which possess the specified property and of which A is a subset. 

verb
  • To hit (a ship) in the hull with cannon fire etc. 

  • To remove the outer covering of a fruit or seed. 

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