deadbolt vs unbolt

deadbolt

verb
  • To fasten or secure with a 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. 

unbolt

verb
  • To unlock by undoing the bolts of. 

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