covering vs leaf

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. 

leaf

noun
  • A sheet of any substance beaten or rolled until very thin. 

  • Anything resembling the leaf of a plant. 

  • A flat section used to extend the size of a table. 

  • One of the teeth of a pinion, especially when small. 

  • The layer of fat supporting the kidneys of a pig, leaf fat. 

  • A Canadian person. 

  • The usually green and flat organ that represents the most prominent feature of most vegetative plants. 

  • A moveable panel, e.g. of a bridge or door, originally one that hinged but now also applied to other forms of movement. 

  • A foliage leaf or any of the many and often considerably different structures it can specialise into. 

  • A sheet of a book, magazine, etc (consisting of two pages, one on each face of the leaf). 

  • Tea leaves. 

  • In a tree, a node that has no descendants. 

  • Cannabis. 

verb
  • To divide (a vegetable) into separate leaves. 

  • To produce leaves; put forth foliage. 

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