Shift vs deadbolt

Shift

noun
  • A modifier key whose main function is shifting between two or more functions of any of certain other keys (usually by pressing Shift and the other button simultaneously). 

deadbolt

noun
  • A kind of lock in which the bolt (moving portion) is held in position by the cylinder rather than by a spring and so cannot be retracted except by turning the cylinder. 

  • The part of the lock which is moved when the key is engaged. 

verb
  • To fasten or secure with a deadbolt. 

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