safety vs sheath

safety

noun
  • A mechanism on a weapon or dangerous equipment designed to prevent accidental firing. 

  • An instance of a player being sacked or tackled in the end zone, or stepping out of the end zone and off the field, resulting in two points to the opposite team. 

  • The condition or feeling of being safe; security; certainty. 

  • Any of the defensive players who are in position furthest from the line of scrimmage and whose responsibility is to defend against passes as well as to be the tacklers of last resort. 

  • A safety squeeze. 

  • Preservation from escape; close custody. 

verb
  • to secure a firing pin, as in guns, to keep the gun from firing 

  • To secure (a mechanical component, as in aviation) to keep it from becoming detached even under vibration. 

sheath

noun
  • A holster for a sword; a scabbard. 

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

  • 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. 

  • The insulating outer cover of an electrical cable. 

  • One of the elytra of an insect. 

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