From Longman Dictionary of Contemporary Englishclose something ↔ off phrasal verbSEPARATEto separate a road, room etc from the area around it so that people cannot go there or use it The roads into the docks were closed off by iron gates. → close→ See Verb table
Examples from the Corpus
close off• All credit to manager Trevor Francis who boldly selected an attacking side and came so close to pulling off a famous victory.• With the distress and disturbance it's going to cause, they might as well close it off altogether.• This closes the opponent off and presents you with a good opportunity to continue the block into the opponent's face.• Following the killings a military order was issued closing the Strip off for three days.• Had he completely closed him-self off in the fourth grade?• Last week, it seemed Dole was coming precariously close to falling off that tightrope.• Close by a couple were kissing, holding each other close to ward off the cold wind that had sprung up.• I could hardly touch her, and each night she closed herself off with Janir. 