sheath vs trunking

sheath

noun
  • The insulating outer cover of an electrical cable. 

  • The base of a leaf when sheathing or investing a branch or stem, as in grasses. 

  • A holster for a sword; a scabbard. 

  • A condom. 

  • The foreskin of certain animals (for example, dogs and horses). 

  • A tight-fitting dress. 

  • Anything that has a similar shape to a scabbard that is used to hold an object that is longer than it is wide. 

  • One of the elytra of an insect. 

trunking

noun
  • Plastic conduit or duct used to conceal and protect electrical wiring. 

  • The movement of containers or packages between a terminal and a transporter's inland facilities, or the scheduled transportation service between locations. 

  • All the electrical and communications cables bundled together and distributed through a building. 

  • A system of ducts for cables, heating or ventilation. 

  • A two-way radio technique that uses a control channel to automatically assign frequency channels to groups of user radios. 

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