block off in WordNet English dictionary

1. render unsuitable for passage
   "block the way"; "barricade the streets"; "stop the busy road"
   barricade  block  blockade  stop  block off  block up  bar 
   
2. obstruct access to
   blockade  block off 
   
3. block off the passage through
   "We shut off the valve"
   shut off  block off  close off