roof over head vs safety

roof over head

safety

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. 

noun
  • 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. 

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

  • 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. 

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