concealment vs covering

concealment

noun
  • The condition of being hidden or concealed. 

  • The practice of keeping secrets. 

  • protection from observation or surveillance. 

covering

noun
  • That which covers or conceals; a cover; something spread or laid over or wrapped about another. 

  • Action of the verb to cover. 

  • A continuous map onto a topological space X, 𝜋:E→X, such that there exists a discrete space D and for every x∈X an open neighborhood U⊂X, such that 𝜋⁻¹(U)= displaystyle bigsqcup _(d∈D)V_d and 𝜋|_(V_d):V_d→U is a homeomorphism for every d∈D. 

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